I have noticed odd stuff in some minor league players. There are a ton of catcher/infielders and catcher/centerfielders. When I look at one of these guys at random, they may not actually have played some of those positions, especially centerfield.
Lavern Grace is one of them, he's rated at C and CF. No real evidence he ever played CF.
Glen Clark is another guy who probably shouldn't have a 50 at CF.
John Taylor actually did play C and SS in the minors (he was a terrible SS with an .821 fielding pct, but rates a 55 defense) - but he never played RF or OF in the real world, but he's rated there.
Carlos Morales seemed to be an outfielder for the Pirates in 1956, but in OOTP in 1962, he's rated at C and SS.
Gail Henley played nothing but OF in the real world, but somehow he's a C/CF in OOTP. (He's never actually played C in OOTP either, so these ratings don't seem to be from in-game usage nor do any of the ones before).
Michael Deaton was a pitcher and catcher in real life. Somehow he didn't get a pitcher defense rating, but he did at LF, CF and RF despite never playing OF.