to go right back up with your off-hand when your head is directly under the backboard and you catch the ball with your shoulders perpendicular to it, or even slightly facing away from the baseline. You've in essence got to move toward the defense to get yourself in any kind of position to hit the shot while not being able to shield the ball with your body, so the tendency is to hurry it. No angle to use the backboard, and you don't want to stuff yourself with the bottom of the rim, so it's hard not to put so much on it that it just goes over the rim.

(Can you tell I've missed a few of those and had time to think about it (on the bench) a while? )