Well his game must have really changed as I saw him at the AO this year and his serve was not huge, and he never served and volleyed, actually he hardly ever came to net. He is just a typical baseliner, very flat hitter.
I guess that's what pro tennis is today, the baseliners are just too strong. Maybe he had to adjust his game when he moved out of college and faced stronger comp. I think I overstated the serve a bit, it was huge for college, particularly for a little guy, I'm guess that just makes him a middle-of-the-road pro server.