Ryan,
Tour says 2.25%, Pete Dye (after converting his inches per foot to percent) says 2.25%, and my experience says 2.25%. I think I will go for 2.25% max slope on cupping areas of most greens.
Actually, the PGA and Masters had a system, at least at one time, where a digital level, placed twice at 90 deg. at any proposed pin spot should read 5.5 or less (back half of green) and 5.0 max on the front half of the green, or if 0% in one direction, 4% in the other. If you figure a 2.75% slope each way (or 2.5% on the green front) and recall your high school geometry, you find that the maximum slope will come in just under 4%, technically 3.89%, or at 2.5% each way, about 3.54%.
Whenever I have gone to a course with 13 greens, and measure cup locations members complain about, they exceed 5.5 total on the cross measurement. Borderlines come in at 5-5.4 total measurements. A 2.25% down slope, with 2.25% cross slope would come in at a real max slope of 3.18%, and I can see why the USGA recommends 3% slopes as the max for cupping for average players.
If steeper slopes potentially "embarrass" top players, imagine how the bottom of the field and average golfers feel?
Some complain my greens are too steep, and my swales are still at 1.8-2.25%, whereas some pros are using 1.5% swales, which I don't believe drain well enough, but at those grades, no one complains except the superintendent.
That's how I view it anyway. My clients can't typically afford to build a lot of green for showy effect, nor do they want to water and spray more than they have to, so they want them all cuppable, generally about 6-6500 SF. To me, the 4+% greens TD does are just wasted, in my specific applications. Sure do look neat though! If I had a sand site, or cheap sand, I would try to convince my client that big greens would be a competitive advantage over other courses. If the super or management company was already on board, not sure it would fly, but I would try.