[jyl]

In many sports, the answer is going to be predictable. A good tennis player will focus on the ball when it is coming toward him, and on the opponent when the ball is going away from him. A slalom skier will focus on the next gate. To take it to a ridiculous extreme, do we need eye tracking tech to figure out what an Olympic shooter is focused on?

In other sports, the answer is probably not important. Does it really matter what a marathon runner is looking at, and is he really looking or do his eyeballs simply happen to be pointed in that direction?

Other sports, mostly team sports, are not as simple, and that's where this technology would be cool. In football, what is the quarterback's progression of reads?. When the point guard brings the ball up the court, what is he focused on? Soccer, volleyball, etc.

In some cases, the players eyes probably flick around so quickly, and he relies so much on peripheral vision and spatial awareness, that it might be hard to follow the dot. For example, Magic throwing a no-look pass.