It seems to me this year's setup of #2, by negating the rough and by playing so firm and fast as to negate the extra length of the course relative to its par (not that they pushed the tees back to the limit anyway), basically clarified the challenge. You're going to miss these greens. You're going to hit and not hold these greens. You're going to see chips, pitches, bunker shots, putts, everything rolling off these greens. And you're going to have nerve-wracking tricky up-and-down opportunities from within 30 yards of the green much more often than you're going to have wicked fast two-putt par opportunities.
So what Martin Kaymer did was simplify and clarify his game to match. He went all in with the putter. Putter from just off the green, putter from good lies, bad lies, sparse lies. Putter in situations that made the NBC expert commentators question his manhood. Putter from places even I wouldn't use a putter (and I use putter from everywhere).
Like any simple, head-on tactic for meeting a clear-cut challenge it comes down to execution. Lo and behold a pretty good putter and terrible (by Tour standards) "scrambler" just whittled away hole after hole on the scorecard by hitting his fade tee shots, hitting one of his fade long irons and the putter, putter, putter until the ball is holed. Now the fact is, if he had putted just like an average Tour player from 6, 8, 10 feet all week he'd have been slugging it out with the +1/E/-1 contingent down the closing holes. But heck if Retief Goosen had putted like a mere mortal at Shinnecock someone else would have won that one.
We know majors come down to putting more often than not. Kaymer just took that to another level and decided if you've got to win majors with your putter then best to get started sooner rather than later. He became the ultimate hedgehog...he just needed to know how to do one thing and he did that thing very, very, very well. Imagine how much simpler his mental and emotional process was every time he missed a green over the weekend. He already knew what shot he was going to play (with very few exceptions) so there's no doubt, no back and forth with the caddie, no five minutes of practice strokes trying to find just the right feel with a wide-open wedge. It was just keep doing the exact same thing for four days in a row....
...and keep making those 8-footers for par. It was brilliant. If the course had slammed 4" deep Bermuda up to within inches of the putting surfaces then presumably he would have needed a steady diet of mini-explosion lob wedge gouges instead of off-the-green putts. There have been plenty of US Opens won by executing those shots very, very, very well. I enjoyed seeing someone get a chance to use a somewhat novel tactic that in fact is as old as the game itself.
P.S. Remember when Todd Hamilton won his Open at Troon (wasnt' it)? He would hit that 16-degree hybrid off the tee, then hit the same hybrid again and if he missed a green he's chip/putt with the same hybrid. I love it when someone pulls out a "hedgehog" tactic like that and executes it to perfection. I think it's cool.