In terms of actual player rating, I didn't see any that looked very underrated. If anything, I'd say Rondo is highly overrated with a rating in the high 80's, but he plays about right, although I think it's a little bit too easy to score with Rondo.
Ray's shot is incredibly easy as long as you're used to it; KG's shot takes longer than it should but it's pretty good too, and KG is way better in the post in 2k11 than he is in real life. Jermaine is incredibly overrated in 2k as well.