Obviously this is totally a hypothetical shot in the dark. A lot of things would have to take place for this move to happen. Mainly Ted Thompson would have to decide to move on from Dom Capers(unlikely) and Rex Ryan would need to get fired. (very likely)
Sure the Jets have been a mess for the past two years in the fallout of Sanchez/Tebow/Geno-mania, however the defense has always been the heart of that team in Ryan's tenure. Let Rex get back to doing what Rex does best and coach defense. The beautiful thing about the way Rex coaches D is he uses a base 3-4 defense, yet has almost endless sub-packages and finds creative ways to implement schemes and use personnel. Not only does he have a chess-like defensive mind, but he is able to foster relationships with the players and motivates the team to play their hearts out. I think if you pair one of the best defensive minds in Ryan with one of the best offensive minds in McCarthy you'd have an explosive unit that would win a ton of games.
With that said...stayed tuned for a "Hire Lovie" post.