Q&A with Mark Broadie [pga.com]

**nevets88** · July 23, 2015

I read somewhere in TST about DJ and his putts/green vs strokes gained putting, but never read anything in the press about DJ's putting stats @ John Deere . Here it is. Most of the rest is probably stuff you already have read, but I forgot some of it, so it's a refresher.

BROADIE: The PGA TOUR is working on splitting strokes gained: tee-to-green into strokes gained: around-the-green, strokes gained: approaches and strokes gained: off-the-tee, to give a little bit more detail about different shots between the tee and green.
PGATOUR.COM: Give an example of where strokes gained provides superior analysis than traditional statistics.
BROADIE: The advantage of strokes gained: putting over other stats shows in Dustin Johnson’s play this season. Through the John Deere Classic, he is ranked very high in putts per round and putts per green in regulation and very low in strokes gained: putting. He is second in putting average (putts per GIR) and 13th in putts per round and, in strokes gained: putting, he’s ranked 125th. Those are huge differences. One says he looks like the best putter on TOUR and one says he is below average, and which would you believe? I think most people who have seen Dustin Johnson play would believe the strokes gained: putting over the other statistics.
There’s a simple reason for that. He’s such a good ball-striker, and has such a good short game, that his putts start way closer to the hole than an average TOUR player, so he takes fewer putts and he takes fewer putts per greens in regulation not because he’s a better putter but because he’s starting closer to the hole. Strokes gained: putting takes it into account that if you’re starting from 10 feet versus 15 feet, you’re on average going to take fewer putts. So when you adjust or control for the initial distance of the putt, it’s a much more accurate reflection of the skill, which shows that he is a slightly below-average putter.

http://www.pgatour.com/link-to-the-future/2015/07/22/mark-broadie.html

**MEfree** · July 23, 2015

I'm glad they will be breaking up the strokes gained tee to green into 3 separate categories. The strokes gained putting stat is definitely an improvement over the traditional putting stats (although it isn't perfect as it doesn't take into account the type of putt you have- straight, up, down, side hill). The introduction of SG tee to green seems to have simply subtracted strokes gained putting from the fields average score, so this doesn't really tell anybody anything that they couldn't have already figured out. The new categories will provide additional insight about a player's strengths and weaknesses (although it likely won't factor in angle to the pin, short-side vs good leave, etc).

**Missouri Swede** · July 23, 2015

It seems that all of the analyses add some info (strokes gained, putts per round, putts per GIR) about a player's performance.

To set up a hypothetical player (taking Broadie's explanation of DJ to an extreme): If a player hit all of his approach shots to 1 foot of the hole and then one putted, he wouldn't have a good SG putting rating (because the putt is never very long/difficult); i.e., he didn't gain any strokes over the rest of the field by making that one putt one each hole. All of the players (more or less) would make those putts.

So our hypothetical player could still be an abysmal putter and make all of those putts. But he doesn't need to gain any strokes by putting--even if he were able to sink putts from 25 feet every time on the practice green, his tournament scores wouldn't improve (because our hypothetical player never has to make those long putts during a tournament). So for him, striving to improve his SG putting stat wouldn't help (separation value).

Obviously, the hypothetical player doesn't exist in reality--every player has to make a variety of putts. I'm just trying to point out that even though SG putting might show the hypothetical player to be a below-average putter, it (the SG number) might be lower in the list of problems that need to be fixed. (Fix the player, not the number.)

**MEfree** · July 23, 2015

@Missouri Swede, your hypothetical player would be an average (or very slightly above) putter according to SG putting.

**Abu3baid** · July 23, 2015

Yeah, we had that discussion in the B open thread.. The above summarizes it perfectly!

**Missouri Swede** · July 23, 2015

@Missouri Swede, your hypothetical player would be an average (or very slightly above) putter according to SG putting.

Yep, or even below average. That's my point.

**MEfree** · July 23, 2015

Yep, or even below average. That's my point. :-)

No if a guy was 18 for 18 on 1 foot putts (or putts of any length) he would be in the top half of strokes gained putting (not factoring in any weird adjustments). i.e. if the tour average is 1.0 putts from 1 foot, then a guy who makes all 18 one footers would have a 0.0 (aka average) strokes gained putting for the round. However, if the tour average was 1.01 for 1 footers, then he would have gained .18 strokes putting (and be considered an above average putter).

**Missouri Swede** · July 23, 2015

No if a guy was 18 for 18 on 1 foot putts (or putts of any length) he would be in the top half of strokes gained putting (not factoring in any weird adjustments). i.e. if the tour average is 1.0 putts from 1 foot, then a guy who makes all 18 one footers would have a 0.0 (aka average) strokes gained putting for the round. However, if the tour average was 1.01 for 1 footers, then he would have gained .18 strokes putting (and be considered an above average putter).

Okay, now I got it. Thanx.

**RandallT** · July 24, 2015

Yah, I'm excited about this. I've been following along with how Broadie has been steering the data analysis, and it has been apparent for a while that the direction was to analyze strokes gained away from the green in the same way that strokes gained has worked for the green. It'll be great to see how pros stack up against each other in more detail.

It'll also be cool to see how each course stacks up against others. Are there courses where the best drivers of the ball win regularly? Best putters? Best short irons? Maybe each course tends to favor different styles of players, and we will be able to analyze the leaderboards to see where the top players for that week differentiated themselves from the field. Even if we knew that info already in our gut, this will confirm those thoughts and give us a measurement of what we felt was happening.

I started a spreadsheet earlier this year that I've been chipping away at (using Broadie data for all shots, not just putting). Here's the summary for my rounds this year- I find it useful to see where I need to improve. I think it breaks down similarly to his categories:

***iacas*** · July 24, 2015

I've been following along with how Broadie has been steering the data analysis, and it has been apparent for a while that the direction was to analyze strokes gained away from the green in the same way that strokes gained has worked for the green. It'll be great to see how pros stack up against each other in more detail.

Well, yeah, he's been doing these stats himself for a few years now, so… they're just going to use his formula from there.

There are some holes, too. He considers all lies in the rough fairly equivalent - he doesn't seem to care if your ball is in the rough behind a tree or with a clear look at the green, etc. So you'll get the same type of strokes gained (if it's a long drive) or lost (because it's in the rough) on that tee shot when the difference could be huge.

**DrvFrShow** · July 24, 2015

I need to start putting for dough. lol. That means chipping and pitching closer to the hole. I need a short game refresher lesson and more practice there. Hitting longer and more accurate drives? I didn't believe it. I'm a believer now.

**RandallT** · July 25, 2015

Quote:
Originally Posted by RandallT

I've been following along with how Broadie has been steering the data analysis, and it has been apparent for a while that the direction was to analyze strokes gained away from the green in the same way that strokes gained has worked for the green. It'll be great to see how pros stack up against each other in more detail.

Well, yeah, he's been doing these stats himself for a few years now, so… they're just going to use his formula from there.

There are some holes, too. He considers all lies in the rough fairly equivalent - he doesn't seem to care if your ball is in the rough behind a tree or with a clear look at the green, etc. So you'll get the same type of strokes gained (if it's a long drive) or lost (because it's in the rough) on that tee shot when the difference could be huge.

I agree with that there is a problem in using their data for balls in the rough. You know me, I'm a skeptic on everything. From what I've seen the numbers that they are using for shots from the rough are too penal relative to shots from the fairway. I also suspect that using his numbers, it makes amateurs look better around the greens than we really are. You've seen some of my spreadsheets that use Broadie's numbers, and that's just my gut feel so far. It might even be significant enough to make my spreadsheet effort worthless (heaven forbid!).

Here are the "Expected Strokes" from distances for tee, fairway, and rough.

Yards	Tee	Fairway	Rough
100	2.920	2.800	3.020
110	2.955	2.825	3.050
120	2.990	2.850	3.080
130	2.980	2.880	3.115
140	2.970	2.910	3.150
150	2.980	2.945	3.190
160	2.990	2.980	3.230

What jumps out at me is that pros get down in 3.0 from just about 170yds from the tee or fairway... but from the rough, they need to be inside 100yds. Your statement about the rough has been something that has been bugging me about his data for a while.

There's a similar thing going on for short game that I can't pinpoint yet. From my 5 rounds this year using his numbers, I'm damn near pro level around greens, but I can assure you I am not!!!! So either there's an issue with the data, or my spreadsheet analysis is wrong.

Anyway, my point is not to derail the discussion into the nitty-gritty of Broadie's numbers, but to suggest that while there is general "worship" (too strong a word?) for anything related to him and his statistics, I think there is always reason to be suspect that it is necessarily going to be a pure answer that we get from it all. Golf is still every bit as much art as it is science, due to the unique nature of every shot, every course, every weather condition.

**MEfree** · July 25, 2015

I agree with that there is a problem in using their data for balls in the rough... There's a similar thing going on for short game that I can't pinpoint yet. From my 5 rounds this year using his numbers, I'm damn near pro level around greens, but I can assure you I am not!!!! So either there's an issue with the data, or my spreadsheet analysis is wrong.

As far as short game goes, my guess is that the courses/pin positions/green firmness/green speed you play are much easier to get up and down on than the courses/pin positions/green firmness/green speed the pros play on. If a pro played where you do, his scrambling numbers are likely to be much better than on tour. The one exception might be that your greens don't putt as true. As far as the pros not doing as well from the rough as you might expect, it appears that shots from the rough not only include straight forward shots from light rough, but times they have deep rough, tree trouble, bad angles to tucked pins, etc. On a PGA tour course, I don't find it that surprising that being off the fairway costs you ~1/4 shot compared to being the same distance on the fairway.

**natureboy** · July 25, 2015

So our hypothetical player could still be an abysmal putter and make all of those putts. But he doesn't need to gain any strokes by putting--even if he were able to sink putts from 25 feet every time on the practice green, his tournament scores wouldn't improve (because our hypothetical player never has to make those long putts during a tournament). So for him, striving to improve his SG putting stat wouldn't help (separation value).

For the 'average' tournament course in average conditions that's probably accurate, but for tricky greens (very firm, contoured, bumpy grass) where a great ballstriker will have first putts on average further than typical from the hole that skill (or lack thereof) would be in play in terms of separation value (Spieth v. DJ at U.S. Open e.g.)

Yah, I'm excited about this. I've been following along with how Broadie has been steering the data analysis, and it has been apparent for a while that the direction was to analyze strokes gained away from the green in the same way that strokes gained has worked for the green. It'll be great to see how pros stack up against each other in more detail.

It'll also be cool to see how each course stacks up against others. Are there courses where the best drivers of the ball win regularly? Best putters? Best short irons? Maybe each course tends to favor different styles of players, and we will be able to analyze the leaderboards to see where the top players for that week differentiated themselves from the field. Even if we knew that info already in our gut, this will confirm those thoughts and give us a measurement of what we felt was happening.

I started a spreadsheet earlier this year that I've been chipping away at (using Broadie data for all shots, not just putting). Here's the summary for my rounds this year- I find it useful to see where I need to improve. I think it breaks down similarly to his categories:

How did you account for the difference between your short game definition (<60 yards) and Broadie's (<100 yards)? Did you have to tweak how you used the tables?

Well, yeah, he's been doing these stats himself for a few years now, so… they're just going to use his formula from there.

There are some holes, too. He considers all lies in the rough fairly equivalent - he doesn't seem to care if your ball is in the rough behind a tree or with a clear look at the green, etc. So you'll get the same type of strokes gained (if it's a long drive) or lost (because it's in the rough) on that tee shot when the difference could be huge.

That's not quite correct. He does have a full strokes gained table that has values for fairway, rough, sand, and recovery lies. His computer algorithm calculates a recovery lie from course data and historical score 'penalty' of other players being in that location. For any of us not being 'shotlinked' it's more of a qualitative assessment so not as statistically accurate, but better than using only a binary fairway / rough calculation.

I agree with that there is a problem in using their data for balls in the rough. You know me, I'm a skeptic on everything. From what I've seen the numbers that they are using for shots from the rough are too penal relative to shots from the fairway. I also suspect that using his numbers, it makes amateurs look better around the greens than we really are. You've seen some of my spreadsheets that use Broadie's numbers, and that's just my gut feel so far. It might even be significant enough to make my spreadsheet effort worthless (heaven forbid!).

Here are the "Expected Strokes" from distances for tee, fairway, and rough.

Yards

Tee

Fairway

Rough

100

2.920

2.800

3.020

110

2.955

2.825

3.050

120

2.990

2.850

3.080

130

2.980

2.880

3.115

140

2.970

2.910

3.150

150

2.980

2.945

3.190

160

2.990

2.980

3.230

What jumps out at me is that pros get down in 3.0 from just about 170yds from the tee or fairway... but from the rough, they need to be inside 100yds. Your statement about the rough has been something that has been bugging me about his data for a while.

There's a similar thing going on for short game that I can't pinpoint yet. From my 5 rounds this year using his numbers, I'm damn near pro level around greens, but I can assure you I am not!!!! So either there's an issue with the data, or my spreadsheet analysis is wrong.

Anyway, my point is not to derail the discussion into the nitty-gritty of Broadie's numbers, but to suggest that while there is general "worship" (too strong a word?) for anything related to him and his statistics, I think there is always reason to be suspect that it is necessarily going to be a pure answer that we get from it all. Golf is still every bit as much art as it is science, due to the unique nature of every shot, every course, every weather condition.

Remember that the strokes gained tables are based on PGA pros. Some of his/colleague's papers talk about the difference between pros and ams out of the rough. Basically, it is a larger penalty for pros - in the neighborhood of losing ~ 50 yards of distance for most (~68%) approaches. Pros are more precise to begin with and they generate more spin from fairway lies so rough interference is more costly relative to a fairway lie to their scoring. But I would bet they are still more accurate out of rough than most ams or even scratch (on the same course) even though a higher HCP's 'rough penalty' is lower. At my HCP it's very roughly the equivalent of losing ~ 5 yards on the fairway.

Broadie also defines 'short game' as inside 100 yards which might affect your numbers or analysis. Also, his statistical baseline leans heavily on data collected on 'championship' courses. In other words, pro setups on generally tougher than average courses. I think it's likely that the pros would still perform better than you (and their statistical average) on the courses you've collected data for.

I agree that Broadie's numbers aren't perfect. But that doesn't mean they aren't really useful or insightful. For amateurs (above scratch) tracking progress. I think his best contributions are his GIRP (Green in regulation plus one), and his 'awful shots' (total, long game, & short game) tables that give baseline numbers by HCP. If you haven't I strongly recommend incorporating that data into your charts. You can find them in some of the tables I've posted in other threads.

**RandallT** · July 25, 2015

How did you account for the difference between your short game definition (<60 yards) and Broadie's (<100 yards)? Did you have to tweak how you used the tables?
.....
Remember that the strokes gained tables are based on PGA pros. Some of his/colleague's papers talk about the difference between pros and ams out of the rough. Basically, it is a larger penalty for pros - in the neighborhood of losing ~ 50 yards of distance for most (~68%) approaches. Pros are more precise to begin with and they generate more spin from fairway lies so rough interference is more costly relative to a fairway lie to their scoring. But I would bet they are still more accurate out of rough than most ams or even scratch (on the same course) even though a higher HCP's 'rough penalty' is lower. At my HCP it's very roughly the equivalent of losing ~ 5 yards on the fairway.

Broadie also defines 'short game' as inside 100 yards which might affect your numbers or analysis. Also, his statistical baseline leans heavily on data collected on 'championship' courses. In other words, pro setups on generally tougher than average courses. I think it's likely that the pros would still perform better than you (and their statistical average) on the courses you've collected data for.

I agree that Broadie's numbers aren't perfect. But that doesn't mean they aren't really useful or insightful. For amateurs (above scratch) tracking progress. I think his best contributions are his GIRP (Green in regulation plus one), and his 'awful shots' (total, long game, & short game) tables that give baseline numbers by HCP. If you haven't I strongly recommend incorporating that data into your charts. You can find them in some of the tables I've posted in other threads.

I did not in any way account for his different definition of short game. I strictly log the lie and distance of every single shot of mine, comparing to the resulting lie and distance. Then calculate the strokes gained or lost for that shot. My thought is that if he defines short game as 100yd, that would be irrelevant. I simply categorize my shots that are inside 60yds, but off the green. For those shots, I lost only 1 stroke per round- even though I had 15 opportunities per round. The 60yds is arbitrary, of course, but I could've picked anything without needing to adjust his tables, right?

Very interesting stuff in bold, as always. I've dabbled in identifying and reporting on "flubs" but haven't completed the thought or implementation. That might match his "awful shots" idea. I'll read into GIRP, but that sounds a lot like nGIR.

I think that yes, the pro game is quite different than the one I play so direct comparison is tough for the reasons mentioned, but I've heard there will be "strokes gained" numbers (expected shots to hole out) released for different handicaps, so I've built my spreadsheet with an eye toward the ability to swap in the comparison you want to make (pro/80/90/100 player). Hopefully those numbers are forthcoming someday.

**natureboy** · July 25, 2015

I did not in any way account for his different definition of short game. I strictly log the lie and distance of every single shot of mine, comparing to the resulting lie and distance. Then calculate the strokes gained or lost for that shot. My thought is that if he defines short game as 100yd, that would be irrelevant. I simply categorize my shots that are inside 60yds, but off the green. For those shots, I lost only 1 stroke per round- even though I had 15 opportunities per round. The 60yds is arbitrary, of course, but I could've picked anything without needing to adjust his tables, right?

Very interesting stuff in bold, as always. I've dabbled in identifying and reporting on "flubs" but haven't completed the thought or implementation. That might match his "awful shots" idea. I'll read into GIRP, but that sounds a lot like nGIR.

I think that yes, the pro game is quite different than the one I play so direct comparison is tough for the reasons mentioned, but I've heard there will be "strokes gained" numbers (expected shots to hole out) released for different handicaps, so I've built my spreadsheet with an eye toward the ability to swap in the comparison you want to make (pro/80/90/100 player). Hopefully those numbers are forthcoming someday.

Fair enough. I thought you might be comparing to his summaries / analyses in which case the relative contributions to scoring from the different 'categories' may differ from his.

How did you deal with inside 10 yards on short game...interpolate off the existing curve or just use the putting numbers?

I'm not familiar with it, but I expect that as others have said that GIRP is similar to nGIR. The nice thing about GIRP (which may also be true for nGIR) is that you can calculate a very nice sigmoid curve (demonstrating the learning curve) for it through all HCPs and because it happens less frequently with low HCPs is actually a more ideal measure (more accurate indicator because it happens more) for mid to high HCP progression to better scoring than GIR.

My GIRP, GIR, and Par-3 GoFIR percentages are all aligned about 7 HCP points below my actual HCP underscoring my issues with putting skill and short game consistency (very high # of 'awful' short game shots) which I've been working to reduce.

I am also hopeful that he will release some amateur tables as well...at least for scratch on a 'typical course', which is generally the benchmark we are comparing ourselves to, but 80/90/100-shooter would round out the picture helpfully.

**RandallT** · July 27, 2015

Quote:
Originally Posted by RandallT

I did not in any way account for his different definition of short game. I strictly log the lie and distance of every single shot of mine, comparing to the resulting lie and distance. Then calculate the strokes gained or lost for that shot. My thought is that if he defines short game as 100yd, that would be irrelevant. I simply categorize my shots that are inside 60yds, but off the green. For those shots, I lost only 1 stroke per round- even though I had 15 opportunities per round. The 60yds is arbitrary, of course, but I could've picked anything without needing to adjust his tables, right?

Very interesting stuff in bold, as always. I've dabbled in identifying and reporting on "flubs" but haven't completed the thought or implementation. That might match his "awful shots" idea. I'll read into GIRP, but that sounds a lot like nGIR.

I think that yes, the pro game is quite different than the one I play so direct comparison is tough for the reasons mentioned, but I've heard there will be "strokes gained" numbers (expected shots to hole out) released for different handicaps, so I've built my spreadsheet with an eye toward the ability to swap in the comparison you want to make (pro/80/90/100 player). Hopefully those numbers are forthcoming someday.

Fair enough. I thought you might be comparing to his summaries / analyses in which case the relative contributions to scoring from the different 'categories' may differ from his.

How did you deal with inside 10 yards on short game...interpolate off the existing curve or just use the putting numbers?

I'm not familiar with it, but I expect that as others have said that GIRP is similar to nGIR. The nice thing about GIRP (which may also be true for nGIR) is that you can calculate a very nice sigmoid curve (demonstrating the learning curve) for it through all HCPs and because it happens less frequently with low HCPs is actually a more ideal measure (more accurate indicator because it happens more) for mid to high HCP progression to better scoring than GIR.

My GIRP, GIR, and Par-3 GoFIR percentages are all aligned about 7 HCP points below my actual HCP underscoring my issues with putting skill and short game consistency (very high # of 'awful' short game shots) which I've been working to reduce.

I am also hopeful that he will release some amateur tables as well...at least for scratch on a 'typical course', which is generally the benchmark we are comparing ourselves to, but 80/90/100-shooter would round out the picture helpfully.

There's another thread that I think I may have mentioned you on where we are discussing our own methods of stats tracking, and I'll answer you there, if you don't mind. This thread was more about Broadie and the PGA direction for stats tracking, so I'll try not to clog it up with my own personal stuff.

(http://thesandtrap.com/t/83225/a-way-of-keeping-stats-thoughts/0_30#post_1174798)

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