box out their best rebounder, usually teams have one guy getting like 20 rebs. Try to push them out long before the shot, if they ever go under the rim trap them there. If you're giving up 30 offensive rebounds a game, I mean, that's what I'd do. I'd pick a big guy off ball, get used to boxing out, and get rebounds so you don't just get trashed.
To answer the post and offense reb question with the same answer, good offense leads to offensive rebounds. There is some crap I'm pretty sure programmed into 2k ( haha) that makes that true, but what I mean is, assuming that is untrue, look at where your guys are before you shoot, keep in mind if someone is turned as a defender, just attack their body, it will get you a foul or perhaps an offensive rebound for your big man.
A good starting move for scoring in the post is to back down and push, I think it'd be like diagonal toward the baseline away from the hoop. Your guy will turn to either side and shoot a one handed shot off of the glass that almost any player can make. It's also not something that gets blocked very often.
The post spin in this game is really powerful as well if it's leveled up enough. But yea some of the weird misses under the rim are just 2ks way of making the percentages seem realistic.
-Smak