He was trying to avoid a pass interference call, realizing he would hit the receiver before the ball arrived. But instead of putting on the brakes (extremely difficult once momentum is increased) he went low. He slid into his teammate who was coming across and would have otherwise had a shot at the tackle or a shove out of bounds before the goal line. Bad luck for the kid; with better timing of defender-ball-receiver he’d be the hero instead of the goat.