By Justin Barrasso UFC 272 lacks a title fight, but the welterweight grudge match could be explosive if Covington and Masvidal deliver in the cage. UFC 272 is built entirely around its main event, which has the potential to be explosive–or a massive disappointment. Premier welterweight contenders Jorge Masvidal and Colby Covington meet in a grudge match to settle long-standing issues. While some of the back-and-forth is contrived (I’m jaded, I suppose, from my years covering pro wrestling), there is a big-enough kernel of truth in their frustrations with each other to make this legitimate. Yet…