Lendl seems to have been the final piece of the jigsaw to break Murray into into that amazing group of Federer, Nadal and Djokovic.
Yeah, it's a relatively dry time for the USA, isn't it? I believe it's the giant John Isner who's highest ranked. The only other guy i can think of is Sam Querrey. Mind, i believe they're still both top 20 players. I think 5th ranked down to 40 or 50 are a competitive group between themselves, just a mile behind the top four.
What's changed in recent years? I guess tennis has never been a huge focus even in the high times - everything struggles in comparison to the 'big four'. But i always remember John McEnroe, Jimmy Conners, Andre Agassi, Jim Courier, Michael Chang, Andy Roddick and, most of all, the mighty Pete Sampras.
Just took a quick look at the rankings. There's also Mardy Fish, and then a few others hovering around the top 100. Still better than the Brit men if you take Murray out of the picture, but i expect more from the US.