Originally Posted by thunderkyss
Mercilus is looking right at the QB with the ball in his hands. I doubt he's playing contain (although that was most likely his assignment as they appear to have expected run). Most likely he's thinking screen & doesn't want Charles to get a free release.
It just looks weird because there is a one second long period that Alex Smith is sticking the ball out to air and Mercilus is just staring there looking at him. Like he was shocked that there wasn't anyone there to take the ball and he was caught off guard.