Mook has been great there as a nickel back, but he's still a corner/DB playing a backer type of position. Playing run-heavy offenses like Pitt require a more traditional-sized Whip LB like Shegog. This is where Hunter's versatility could be an asset. Foster wouldn't have to sub out anyone and keep the same personnel on defense the majority of a game.

With that being said, there's a lot of talented DBs on the roster, and Mook is proven as a nickel back. Shegog has done well in his role subbing in as well. Like you mentioned, Reggie Floyd can factor in at Rover as well. The coaches will likely use the spring to experiment as much as they can before the new class arrives in the summer.

IMO, the amount of talent in the secondary is a good problem to have, and building competition is what makes teams even better. Looking forward to the outcomes of the position changes.