[stannis]

I'm not sure what you mean by stats "by position", but if you mean player defensive ratings, then (in OOTP terms):

Catchers have their own skill set; no non-catcher can play this position
First base defensive skills aren't big priorities; almost anyone can play first base and anyone capable of playing another infield position can do so more than capably
Second base needs good Range and ability to Turn Double Plays
Third base needs a good Infield Arm
Shortstop needs good all round infield skills to be competent
Left and right field need average outfield skills, with a stronger premium on Outfield Arm for RF
Centerfield needs good all round outfield skills, and in particular Outfield Range
Of these, the most important are Catcher skills; Turn Double Plays for 2B; good all round Infield skills for SS; and Outfield Range for CF.

If you mean offensive skills, then these aren't determined by position. However, given that C, SS, and CF need good defensive skills, you can justify a weaker batter at these positions. Given 1B and LF require only limited defensive skills, you might want to make sure you're getting the best possible batters into your lineup at these positions.