This is always my fear at a baseball game. I trust myself catching a foul ball. If I can get my hands on it, I'm gonna catch it and it's not gonna fly off my finger tips. I do not however trust the fans around me who are half paying attention and flailing their uncoordinated arms at a line drive foul ball.
That was this guys problem. He trusted the wrong fan in front of him and ended up getting jacked in the melon with a line drive.