With their game against the Memphis Grizzlies tied at 90 with around thirty seconds left, the Mavericks needed a stop to give themselves a chance to win the game.  After the Grizzlies ran an uninspired ISO set, Rudy Gay missed a jumper from the elbow.  However, the Mavericks were unable to secure the defensive rebound due to a poor effort by Tyson Chandler, and it ended up costing them the game:

When Rudy Gay takes his final dribble as he starts to pull up for his jumper, Tyson Chandler seems to be in perfect position to secure the defensive rebound.  He is on the inside, and it seems that he is on a spot on the court where it would be real easy to just turn and box out.

However, Chandler never gets a box-out on Gasol.  Instead, Chandler decides for whatever reason that he wants to hand fight with Gasol instead of turning around, getting his butt into Gasol, and using it to box him out and keep him out of the paint.  There are two real reasons why you don’t want to hand fight when trying to get the defensive rebound.  The first reason is it means you aren’t boxing out.  The second reason is that you can’t use your arms to actually grab the ball, because they are occupied.

And that is exactly what happens here.  Gasol gets his arms free as the ball goes over Chandler’s head, and he is able to snag the rebound.  To make matters worse, Chandler fouls Gasol going for the basketball after the rebound, sending Gasol to the line where he would end up hitting the game winning free throw.

Here is a look from an overhead angle, and it really does a good job of showing you why hand fighting underneath doesn’t work.  Chandler sees the ball coming, but his body and his hands aren’t in a good position to grab the rebound, giving Gasol the advantage.  Here is the play in real time: