There’s a new sheriff or two in Nashville. Along with Tennessee Titans’ second-year head coach Ken Whisenhunt, former Oregon Ducks quarterback Marcus Mariota has joined a freshly assembled Titans’ posse, and is already regarded as THE guy in Tennessee. The NFL franchise that once boasted the careers of Earl Campbell, Warren Moon and Steve McNair, capitalized big time by swooping up the Heisman Trophy-winner at No. 2 in the first …