AB is usually the catch all for guys who are good players but for some reason can't find their way onto the field at the original position they were recruited for. We've had ex WRs (Searcy), ex QBs (Days, almost Jordan), ex/future BBs (Perkins, Ant, QFro), and even an ex DB (Griffin) move to AB.
MM would actually be a devastating rusher at AB because he's so shifty in tight spaces, and he's strong enough to break DB arm tackles, and fast enough to run away from them. Because we are so deep at AB, his value is actually better at BB. Kinda the situation that Gotsis found himself in during his career. Adam should have played SDE for us, would have probably been close to an All American there (if you've seen his early returns in the NFL at SDE, you know why), but necessity had him at DT.
I honestly would cross train MM to play AB and BB for short yardage packages. Who cares if you're tipping the defense, they still have to stop them. A "power" backfield of Griffin/QFRo at AB, Mills at BB, and MM at AB would be awesome to watch, especially on the right with Shamire and Klock.