If the US Open has slipped a bit, I wonder how much of it has to do with the decline in American tennis. After probably being the dominant nation in the After holding year-end #1 ranking in 17 of 26 years from 1974-99 (5 Connors, 4 McEnroe, 1 Courier, 6 Sampras, 1 Agassi), the US hasn't had an elite since Andre Agassi retired eight years ago. Andy Roddick was the closest thing, and he was more of a borderline elite player, at least after Rafa and Novak rose up and pushed him down the rankings.
I wrote about this last year, but there just hasn't been any top American players over the last few years. Mardy Fish? John Isner? Sam Querrey? The younger generation hasn't really blossomed, although Jack Sock looks decent. I suppose there's hope in Jared Donaldson or Francis Tiafoe.