Marcus Mariota
The Titans were set to roll for one more year with Mariota before switching to Tannehill early last season. The No. 2 pick in the 2015 draft could never get his feet all the way under him and he never scratched the ceiling he set for himself with an outstanding college career. The physical tools are all there with Mariota, but he wouldn’t be an upgrade for the 49ers. The only way a player like Mariota would make sense is in a backup role where he might make a spot start or two, but he’s not better than Garoppolo, even in Shanahan’s offense.