Mason Plumlee was trying to watch the weakside action to make sure the Clippers didn't get an easy layup. The only problem is by doing that, he forgot to watch his man, DeAndre Jordan. Jordan made sure Plumlee was aware that was a mistake by charging the rim and smashing a dunk just as Plumlee turned to recover.
Jordan doesn't usually create off the dribble, but if you completely forget about him, things go bad in a hurry.