The way I saw it was that the guy was leaning over the rail to see the ball as it rolled around the corner, identified the ball, and started to raise his right hand in a typical "fist making" gesture of joy, when Sheffield ran his face into the guys hand.  I am not trying to excuse the fact the guy should not have been leaning over the fence.  But I do think you have to be careful in trying to read someone's mind and pre-determining intent.