The average four-round score is a pretty straightforward measure of difficulty with one exception; it can be modified over time. That’s one reason we also look at standard deviation, which normalizes the kinds of weather, course design and equipment changes that make it easier to shoot par today than it was a century ago.
We’ll do that momentarily. But if average score carries a bit of a taint to it, it’s still worth looking at. Besides, all of these courses have hosted the Open over stretches of at least 30 years (Shinnecock), and as much as 100 years with regard to Oakmont. All but Shinnecock and Pebble had hosted their first Open by 1936; that time spread ought to ameliorate the problems that looking at average score might normally present.
From highest to lowest, this table shows the average four-round score of all players at each course through Open history.
Winged Foot 298.90
Oakland Hills 297.65
Pebble Beach 295.11
To really drill down into this category, some adjustments for changing par would be needed. Oakmont, for one, plays today as a par 70, but it began Open life in the 1920s as a par 72 and for much of the time played as a par 71. Pebble has also lost a stroke or two to par over time.
With respect to Winged Foot, however, the raw numbers remain hard to contest. Based on the data, only Oakmont can make the case that it has played tougher, and only by about half a stroke. Winged Foot has consistently played a stroke and a half tougher than any of the other Open regulars, including in 2006, when the field average remained a healthy 293.63.