How does an open setup change the course rating?

[bunkerputt]

Does anyone know roughly how much an open setup makes the course and slope rating go up?  Everyone knows it's tougher, but how tough is it exactly?

[Clambake]

An interesting question, but probably really hard to answer with a general answer as there aren't many courses that host both a US Open and a regular Tour event.     A couple venues to look at are Pebble Beach and Torrey Pines which host both.

Instead of looking at total score, I tried looking at the final round scoring averages and see how they compare since both the ATT and Farmers tournaments also include different courses which impact the winning scores.     So looking at just the final rounds, at Pebble Beach the 2010 US Open played to 74.9 average on Sunday, while the 2011  ATT played to a 73.2 average, suggesting that the Open setup added about 1.7 strokes for the pros.     It is probably slightly more than that as the ATT was played in unusually dry conditions this year so the fairways and greens were already drier than normal and playing more like Open conditions.

Doing the same for Torrey Pines with the 2008 US Open and the 2011 Farmers yielded a different answer.    The final round of the 2008 US Open at Torrey had a scoring average of 72.9 while the final round of this year's Farmers was 72.8.     I do know that this year they set up the Farmers to be tougher than normal by creating much more narrow fairways than in the past, so that probably contributed to the closeness between the Open and normal Tour event scoring.

[TourSpoon]

Originally Posted by bunkerputt

Does anyone know roughly how much an open setup makes the course and slope rating go up?  Everyone knows it's tougher, but how tough is it exactly?

I am interested to know and I am sure someone at the USGA could answer. I was estimating that the rating would be in the high 70s with slope in the mid to high 150s.  Again, just a guess based on what I see as some of the regular tour events are rated at 75 with slopes approaching 150.