Jesse is not a serve and volleyer.
To be honest, this result doesn't surprise me at all. Levine is very green and very young in some ways, even if he went 21-0 in his freshman year at UF. He is also kind of small, 5'8" max when I met him last year at a Challenger, and not very muscular. He has probably grown and developed somewhat in that time, but he will have a LOT of adjusting to do to get up to the level of the guys on tour. He probably should have stayed in college one more year before turning pro, but sometimes a match like this gives you some learning in a hurry.
Well assuming a guy like that wants to raise his confidence Davydenko is probably one of the worst players to face. He returns so well that you aren't going to get those service games as you might with some other top players in early rounds such as Roddick or even Federer at times.
As for the serve and volley it was evident it wasn't exactly natural from watching but he didn't look like he was too upset at such a crushing defeat.