The Titans are confident Mariota will be able to adapt.

"Marcus is a smart guy," Robinson said. "We'll work at it. Whatever we ask of him from a studying and learning and terminology standpoint, I am confident that he'll definitely put the time in to try and be his best."

The Titans missed out on the playoffs in 2018 after losing to the Colts in the season finale, a game Mariota missed because of an injury.

Mariota started 13 of the team's 16 games in 2018, and played in 14 of 16. He finished the year with 2,528 passing yards with 11 touchdowns and eight interceptions. He set the franchise record with a completion percentage of 68.9 %.

"When he was healthy and out there, he certainly gave us a really good chance to win the game, and made some big plays for us," Robinson said of Mariota. "Kind of at the end there, the health and safety of our players is at the top of the list, and we really don't want to put anybody out there that we don't feel like can protect themselves or they're at risk for an injury."

Mariota was ruled out of the season finale because of neck and foot injuries.

At season's end, Vrabel said the decision to keep Mariota sidelined was made by a group of people, and Mariota said himself that's true. Concerns about a nerve injury – and how it could impact his future – played a role, Mariota said.

Robinson said the decision to hold out Mariota was made with the future in mind.

"It was a collective decision," he said. "We talked about it, and talked about it with Marcus and got opinions. I keep coming back to player safety, and I think Marcus is a tough guy. He has played through a lot during his career. I don't question his toughness. He has shown that he loves his team and he wants to be out there with his teammates. But when you are risking something, you have to weigh the future relative to what's the cost of putting him out there.

"It will be important for him this offseason to take some time to get healthy and come back ready to go."

Mariota said the day after the regular season finale he's been told he won't need surgery, just time to heal and get healthy.

When Mariota couldn't play in 2018, the Titans leaned on veteran Blaine Gabbert, who started the season finale and ended up playing in eight games, including three starts. Gabbert's final numbers: 61-of-101 for 626 yards, with four touchdowns, four interceptions and a 74.9 rating.

Gabbert remains under contract through the 2019 season. Robinson didn't discuss the team's thoughts on adding another quarterback to the mix. The Titans drafted Luke Falk in the sixth round of last year's draft, but he was released.

"I thought when he stepped in, he won a couple of games for us – the Washington game and the Houston game," Robinson said of Gabbert. "I thought he was good for the room, I thought he was good for the team. Are there some things he needs to continue to work on? Sure. But I thought he did a solid job in what was asked of him. He prepares like a starter on a weekly basis, and is ready when called upon."