To add some old 1000 level sport psychology to the mix, theres a difference between catching a pop fly ball and catching the same ball when it's the final out to win the World Series. A practiced, autopilot action takes place.. somewhere in the brain. I want to say mid to rear. When you add stakes, and the internal dialogue, "ok, here it come, nice and easy.." it uses... I want to say the front part of the brain. Instead of the part of the brain that does it all the time, he's got a backseat driver yelling instructions. The backseat guy is the guy who will figure out problems the driver has never seen before, but he's just causing confusion in these practiced tasks.

As you can see here, Frank Mir's backseat driver has taken a few shots to the head.