I played a season in APA and started, like everybody else, as a 4. The first week the captain, who's otherwise a good guy, told me to keep the inning count up. I'd never played that way and didn't want to play that way so I thought, fck that, and pretty soon I was a 6. Then he asked me to dump a match so I didn't go to a 7 because the math wouldn't work if I was a 7. I flat-out refused. I told him I'd rather not play at all than tank a match.
IMO, you should either play to win or not play, or find a league where your handicap isn't going to prevent you from being able to play. I've played a lot of BCA and never seen any sandbagging. I'm sure it exists but I've never been witness to it.
I realize this is purely anecdotal, a research survey of one.
But I've heard a lot more about sandbagging in the APA than the BCA, probably because of the 23 rule.
If you want a fun, alcohol-fueled night out with the boys and girls, APA is great. But I think there are better ways to improve your game.