Miami traded Tannehill on Friday to the Tennessee Titans in a deal that also involved draft picks. The Dolphins sent their sixth-round pick this year to the Titans for a fourth-round choice in 2020 and a seventh-round pick in April.
Tannehill turns 31 in July, and his departure from Miami had been expected. He became the starting quarterback as a rookie in 2012 and has still never taken a postseason snap.
His contract was to balloon to $18.7 million in base salary this year, and he would have counted $26.6 million against the salary cap.
The Dolphins are seeking their quarterback of the future under new coach Brian Flores. They have the 13th choice in the April draft, and might devote their first-round pick to a QB for only the second time since 1984.
As a stopgap, Miami is also in the market for a veteran. Free agent Teddy Bridgewater met Wednesday night with the Dolphins to discuss playing for his hometown team, but decided to remain Drew Brees’ backup in New Orleans.
Tannehill, 42-46 as a starter, missed all of 2017 with a knee injury, and sat out five games last year with an injury to his throwing shoulder.
He said at the end of 2018 he wanted to remain with the Dolphins. But owner Stephen Ross fired coach Adam Gase and ordered a roster overhaul while acknowledging it may take several seasons to build a winner.
Miami went 7-9 last year and ranked next to last in the NFL in yards, worst in franchise history.
Tennessee, meanwhile, adds an injury-prone quarterback to the one it has. Mariota, the second overall pick in the 2015 draft, never has played a full NFL season and is 27-28 as a starter.