Tiger Woods has had a spectacular year by all accounts. Five PGA Tour wins and not a single missed cut, but no major victories. And that hurts, sure, but how much? Well, that's what I am here to identify.
There's a relatively simply stat that goes a bit beyond Old Man Par, called "z-score." Z-score is simply a way of comparing how someone scores to how the rest of the field scored. For instance, during Jim Furyk's 59 at the BMW Championship, the average score for all players that made the cut that week was 71.086. Z-score compares the player's score to that average, and uses the standard deviation of the round's scores to measure just how tough the course was playing on a given day. The number that the relatively simple formula spits out is a representation of how many standard deviations a player's score was from the course average. Only the scores from players that made the cut are used, otherwise you would not be able to compare Thursday and Friday rounds to weekend rounds. (Players who missed the cut are, by definition, playing worse, and not having their scores in the weekend course averages would made it look like the course was playing much easier.)
A simple explanation about the ramifications of z-score is that despite shooting a 69 on Saturday and a 67 on Sunday at the TOUR Championship, Tiger's Saturday z-score was actually better because the course played two shots easier on Sunday, and because the field's standard deviation that day was a bit higher.
Using the tournament leaderboards from Yahoo! Sports (the PGATour.com ones were a bit tougher to import into a spreadsheet), I plotted an entire season's worth of z-scores. (You can email or PM me for the full spreadsheet if you'd like.) I calculated the z-score for every player for every round, and then picked out the records of the PGA Tour Player of the Year finalists: Tiger Woods, Henrik Stenson, Adam Scott, Matt Kuchar, and Phil Mickelson.
How did they fare statistically? Read on the find out.
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