Some style items, yeah.
Granderson batting style - Delgado
Casey batting style - A.Rod
Chad Durbin pitching style - M. Morris (this one is dead on)
Zumaya pitching style - I went with Lowe, although Zoom's delivery is pretty generic, actually
Nick Markakis is definitely Reggie Jackson, as has been pointed out. It's a dead ringer.
You may not want to do the following, but I always change Inge's face to 399, Joe Kennedy, because that 620 he has looks like Huck Finn and not Brandon. I also change Zach Miner to 877 Jon Maine because in the game, it resembles him. I installed Jogar's Fernando Rodney face because it's one of the best cyberfaces I've ever seen.
Other than that, just tweaking sliders for All-Star and Pro modes, since I play in all three modes. I use MD 3.1 too.