I really don't know!! It's not as if they smack it around constantly - quite often, they're fairly quiet on the boundaries front...
I don't use any exploits, like pack the offside ringfield so that the AI keeps getting caught there, I don't go fully defensive when the AI's in slog mode, otherwise they just get out too quickly and I save/reload for AI suicide-o-runs. I've got no interest in learning about any 'insta-wicket balls', since that just ruins the game. I usually find 'death balls' by now, but so far I haven't found any in AC 09 and I don't want to know about any either.
If we could just get a few more LBWs/bowled wickets, the edges to behave properly and some more steeplers that go miles in the air and get caught in the covers somewhere, this game will be immense, as far as the bowling side goes. Oh and this 'slog trigger' needs to be found and killed as well.