Ruth, of course. Jason Vargas, sure. Mike Hampton, definitely. Jason Marquis is very good. Dontrelle Willis is having a bad year because he gets pitched to like a hitter. Bob Gibson was a very good hitter. Tony Cloninger once hit two grand slams in an inning. Walter Johnson once hit .425. Don Newcombe hit very well, too.
So the answer is yes. Before 1972, there was no reason for a pitcher in either league not to be able to handle the bat with some ability.