Here are a few Washington Nationals players that are 2K versions which I updated with better facial hair, lightened/darkened, changed skintones. Just unzip each file then copy/paste into your main 2k12 directory. Use Ty's editor to make changes as noted.
What's New in Version Final Version
Danny Espinosa body type to Buff, Average, skintone to 9
Ian Desmond body type to Buff, X-Large, skintone to 7
Bryce Harper body type to Ripped, X-Large, skintone to 3