I'm not a fan of switching players positions unless the move is intended to be permanent. We've done this more than a few times and it doesn't do anyone any justice. IMO, Chris Williams, Izzy, etc. have been stunted a bit by transitions that are far less dramatic than from DE > MLB.
The move from Safety (guy who calls the coverages) to MLB (guy who calls the defenses) is far less of a risk. Also, I'm not sure that Shea has the lateral or vertical speed for any of the LB positions, much less MLB.