From the little I've seen in pre-season, I haven't seen Tolbert move an opposing player until he gets past the line of scrimmage. Which tells me he isn't a great option for short yardage. He doesn't really seem to keep his legs churning, he just weighs a bit more, so he's decent for blocking, or running through a second level defender. JWill might be better suited for short yardage, if he can squeeze through a gap in the line, AND keep his legs moving upon contact.