It’s unclear who will be the first player under center for Kentucky when the Wildcats travel to Knoxville Saturday night for a “dark mode” game at Neyland Stadium. It doesn’t matter if it’s Brock Vandagriff or Gavin Wimsatt, the charged atmosphere will be a challenge against a defense that’s ranked No. 4 in the country by SP+. Coaches love to play coy when it comes to starting quarterbacks. Opposing coaches love to diminish its significance. Tennessee is going to prepare for both players, regardless of who starts first. Josh Heupel knows that whoever is in the game for the Wildcats will be tas…