it is not so very clear in the rules (unless they recently changed) it says that for example guards are weithed heavely on outside D, but not exactly which skills are considered. Knowing it is outside D, the outside D skill of the guards will be in there, but what else...
also respectable is not respectable. your Pg could be 7.9 (respectable) while your center could be 7.0 (also respectable).
Further there is form, it might be that the center was not in a very good shape...
it all adds.
1 thing is for sure: your center did not perform worse just because his best position is center, the game engine does not look at best position at all, it only looks at the skills, would your center, with the exact same form and skills (for some unexplainable reason) be named as PG by BB, he would have performed just the same.
hope this helps...
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