Tannehill's representation, SportsTrust Advisors, announced Friday that the Titans acquired Tannehill and signed him to a one-year contract.
According to NFL Network's Ian Rapoport, the Titans will receive Tannehill and a 2019 sixth-round pick, while the Dolphins are getting a 2020 fourth-round pick and 2019 seventh-round pick in return.
Per ESPN's Adam Schefter, Tannehill's deal with Tennessee is for one year with $7 million guaranteed. It could exceed $12 million based on playing time and other incentives.
In Tannehill, the Titans have a quality backup for the oft-injured Marcus Mariota or perhaps a quarterback who could beat out Mariota for the starting job in an open competition.
Toward the end of last season, Tannehill made it clear he wanted to remain in Miami.
"Of course," he said in a December press conference. "I love this organization. I love the guys on this team. I love competing with the guys on this team. I've been here my whole career and love it in South Florida, love what South Florida brings to the table. So yeah, I'd love to be here."
But going in a different direction at quarterback is the right move for the Dolphins.
Tannehill, the eighth overall pick in the 2012 draft, has had ample time to prove himself as a franchise quarterback. Instead, he has zero Pro Bowl appearances, which is equal to the number of playoff wins for Miami since he became the starter as a rookie.
Over the past seven years, 39 quarterbacks have attempted at least 1,000 passes, according to Pro Football Reference. Among that group, Tannehill is 20th in completion percentage (62.8), 27th in quarterback rating (87.0) and 22nd in yards per game (232.2).
When Tannehill was healthy—he missed all of 2017 after undergoing knee surgery—the Dolphins were never one of the NFL's worst teams, but they seem to have reached their ceiling with him under center.
Tennessee has adopted an aggressive approach in an offseason with a dearth of quality options at quarterback. Nick Foles, Tyrod Taylor and Teddy Bridgewater had previously signed with other teams, taking three of the best free agents off the table.
The Titans likely would have had to draft a quarterback or enter 2019 with Blaine Gabbert as the backup again. Since Gabbert threw just four touchdowns and four interceptions in eight appearances (three starts) last season, a better option was needed.
Mariota has missed at least one game in each of his four NFL seasons, and Tannehill gives head coach Mike Vrabel a backup with a wealth of starting experience should injuries strike again.
As for the Dolphins, Jake Rudock and Luke Falk are the only quarterbacks on the roster. Drafting a quarterback or signing a free agent like Ryan Fitzpatrick, Brock Osweiler or Blake Bortles is a must.