I wouldn't really be worried about his height, he's probably not going to be a world beater in the end. I think he will bring healthy competition and he's a stout 260 though. In the end even if he could be a solid back up his ability to provide depth would be great. Especially if they draft Barnett, Takk, Taco or a future prospect in the first.
EDIT: Not even that if, they draft an OLB in the 2nd, 3rd, ect. Sheard should make an impact as well. I really like what Ballard is doing, I'm going to keep saying it. 7 picks in the first 5 rounds.