Need to ask, did he run over him, did he tackle or rough the place holder? Was he blocked into him? Was ot a case of just not being able to keep from brushing him? After all of those thoughts is a flag warranted? If so running into would cause down to be replayed on miss, declined on good kick by rule. If personal foul, 1/2 distance and rekick, or 15 on kickoff if kick good.