It is not so much size as speed quickness and athleticism that the Packers need to help the ILB. Martinez was a pleasant surprise and Ryan is...well...slow and steady. We saw a lot of Joe Thomas's speed last season. I think frankly he will play more because of that. If ILB injuries mount, look for CM3 to move inside again which may be a better fit for him at this stage of his career as a pure play maker anyways.
Athleticism and speed.