With the last patch, I simmed an entire season using an outfielder as catcher- 1s in all catcher ratings (out of 200). He threw out nearly 30% of basestealers on the year, so I don't find your CS result too surprising. I think there is a game issue with weak C arms; even the weakest-armed catchers seem to be guaranteed a decent CS% (near to break-even, as far as runs allowed), in part, perhaps, because weaker basestealers will test them more often.
I summarized the results here (post 13 compares Wagner, the outfielder-turned-catcher, with other Cs in the league):
http://www.ootpdevelopments.com/boar...d.php?t=151243