PEOPLE MOVING AT HIGH SPEED WITH PARTIAL INFORMATION CAN BE DIFFICULT TO FOLLOW
Miami put a camera on linebacker Denzel Perryman for the Hurricanes' spring game, and it reminds you of a few things. First, even getting to the running back cutting through a forest of linemen is a horrible, awful, and very hard thing to do. Second, that running back might be gunning straight for your sternum, and that in itself can be as terrifying as losing track of him entirely. Third, that play-action, no matter how dumb and obvious it might look from the comfort of the stands, is devastatingly effective because football played out on a whiteboard is a matter of eleven-on-eleven, and on the field is a matter of individuals trying their best not to be confused or fooled in a maze of burly bodies moving at high speed.
TL;DR: Football is hard and very confusing for the people playing it. (Via.)