Matt Cassel appears to be the most likely choice here, although my preference would be a promotion for Alex Tanney – His game (accuracy, arm strength, reads, and athleticism) are more similar to that of Marcus Mariota. That said and despite all of his limitations, Cassel is a safe, game manager that can prevent a team as talented as the Titans from losing.
The remainder of these guys are most likely seeking, at minimum, a QB1-b type opportunity – Not ready to settle for a backup role (clear cut QB2) on a team like Tennessee that has a long term franchise QB in place.