A ball boy in Cleveland decided he would insert himself into the action.
It happens. When it does the umpires can impose any awards or penalties they feel nullifies the act.
3.15 No person shall be allowed on the playing field during a game except players and coaches in uniform, managers, news photographers authorized by the home team, umpires, officers of the law in uniform and watchmen or other employees of the home club. In case of unintentional interference with play by any person herein authorized to be on the playing field (except members of the team at bat who are participating in the game, or a base coach, any of whom interfere with a fielder attempting to field a batted or thrown ball; or an umpire) the ball is alive and in play. If the interference is intentional, the ball shall be dead at the moment of the interference and the umpire shall impose such penalties as in his opinion will nullify the act of interference.
So, if the ball was a rocket that hit him unintentionally the play would continue. In this case, he clearly and intentionally grabbed it so play is dead.
Pretty easy call for the umpire and pretty embarrassing moment for the kid. Instead of ball boys, they should call the foul ball boys so they know only to pick up those.