Also, keep in mind that there is a lot of off-ball movement.
So teams like the Celtics will send Ray Allen back and forth around screens along the baseline to try to get him open in the corners. Most likely, the reason why you're seeing cats wind up open is because their defender gets hung up on a screen (or you're using that guys defender to double team the ball handler). The more you play, the easier it will be to recognize these plays. Remember though, the AI is always adjusting to you. Gotta stay on your toes.
Get in the habit of ball denying the perimeter guys, it helps. Make sure you're facing a guy without the ball on the perimeter and push the right stick in his direction and you'll ball deny. Or if you want to be a little more aggressive, use (not sure exactly which L it is on PS3) but the L trigger (360) to grab the guys jersey. You get called for a loose ball foul sometimes when you do this, though.