Marcus Mariota, the second-overall pick in the 2015 NFL Draft, is in the final year of his rookie deal and will earn $20.9 million in 2019. If he underperforms, not only could the Titans decide to let him walk in free agency, but they could turn to Ryan Tannehill, a 2012 first-rounder with the Dolphins, at some point in 2019.
As it stands, this remains Mariota's team. We know this because coach Mike Vrabel reiterated as much recently.
"[Tannehill's] job as a backup -- everybody's job as a backup -- is to push the guy in front of him," Vrabel said, via UPI.com. "To compete and try to make yourself better and try to make the team better and see how everybody responds."
So what might precipitate a quarterback change? If recent history is any guide it would be because Mariota struggled to stay healthy. He has yet to play a full season because of various ailments, and more than that, only once has he finished higher than 20th among all quarterbacks in value per play. In 2018, Mariota was 27th, behind Nick Mullens and Eli Manning. Tannehill was worse -- 32nd -- but he was an improvement over Blaine Gabbert, who started three games last season in Tennessee for a banged-up Mariota.
The best-case scenario for Tennessee: Mariota avoids injury and plays all 16 games, and Tannehill serves as his backup. And while Tannehill might not love that arrangement he understands it.
"I think there's a lot of mutual respect between us," Tannehill explained back in May, via the Tennessean. "I'm going to try to help Marcus as much as I can. I think Marcus has done the same for me. As long as we have that mutual respect and understanding that we're aligned in trying to push each other and make each other better. Ultimately, we want to help this team win. That's what we're here for as quarterbacks, is to help our team win. Lead the offense down the field and put points on the board. Like I said, we're aligned in that, and that makes all the interactions and the competition a lot of fun."
Tannehill, 30, is five years older than Mariota though neither player has a winning record as a starter. Tannehill is 42-46 and Mariota is 27-28. Only Mariota has taken his team to the playoffs (2017) where his record is 1-1.