Jackson at MLB?

Why hasn't the thought of Rob Jax at MLB come up? I know he plays OLB, but with Orakpo healthy, Kerrigan and now Jenkins, there is less time for him. You want a playmaker like him on the field. He is OK at the run but excels at coverage and London won't be here much longer. I know we all want to keep him and this may be a good way. Riley would become the captain still, but I think Rob could be a pretty good MLB. Thoughts?