very minor, especially at that level. even if its 10% (and its probably 5% or less), when you're talking percentages it isn't a big deal as their attribute levels aren't very high yet.
10% of 50, 30 &, 30 and 20 (total -12) is a lot less than 10% of 100, 80, 80 & 70 (total -31)
IMO you can move guys around quite a bit on defense at the rookie/pee wee level. offense is more tricky.