Young will be better than that rating. The game uses the actual defense of a player. Young has a DP % of .63 per game while Peralta has a .76 DP's per game.

DP's are also affected by DP partner, groundballs per game based of pitching, batters, etc. Everything being equal(which is impossible) I'd see Young with 94 DP's for 150 games and Peralta with 114 DP's. Thus Peralta is 20 DP's better.

Since the game uses actual stats, Arod had a 1.000 fielding rating at SS(no errors). The game still gives him a very slight chance(about 1%) of committing an error, so I could see Arod with only 5-10 errors.

Obviously this is all my opinion, but based on lots of experience.

Bottom line ignore the rating and go with the actual stats(including zone rating).