You probably didn’t know who Mekhi Brown was before last Monday night. The sophomore linebacker entered the College Football Playoff Championship Game with six tackles, most of them on special teams. But then he became momentarily famous — or infamous — for a third quarter stretch in which he punched Georgia player Wyatt Payne, got into a physical altercation with a coach on Alabama’s sideline, then re-entered the game and made a clothesline tackle.