I know this is a deeper draft than most but I think we need to temper our expectations slightly on what we expect to get with the #20 pick. Historically you can expect a player that is somewhere between a role player and a bench warmer at that spot.
If you can get a guy with the pedigree of Barnes (who is still very young in his own right) for that pick and Vasquez, then you probably should think long and hard about it. Barnes just turned 22, and has already had some big moments in an intense playoff environment. He had a disappointing season this year no question but we're not talking about a Derrick Williams level train wreck here either. The Warriors aren't just going to give him away for a second rounder and a bench player.