Mark -
Without getting to a specific US Open course, it is clear that AGNC & the Masters present a much different test of golf than the collective US Open courses. Of the combined total of 20+ major championships won by Seve, Faldo, Watson, Lyle, Langer, Olazabal, etc., the majority have been Masters victories at AGNC. From that group of players, there has been only 1 US Open win (Watson at Pebble Beach).
Contrast that with multiple US Open winners like Hale Irwin, Curtis Strange and Payne Stewart, who have, with one exception, never really contended in the Masters.
DT