After engineering the first fourth-quarter game-winning drive of his quarter, Tannehill took a big step against Seattle, a feat made more impressive because it came against a very good defense.
Tannehill ended the fourth quarter with eye-popping stats: 7-for-8 for 156 yards and a huge 15-yard scramble on the game-winning drive.
It was the kind of thing Dolphins fans became accustomed to when the quarterback was Dan Marino.
Tannehill obviously has a long way to go before reaching Marino status, but it's got to start somewhere. And the Seattle game was a great start.
In time, Tannehill will eliminate the mistakes, like that interception he threw that was taken off the board when Seattle safety Earl Thomas hit him in the head after jumping to try to knock down the pass.
That truly was a bad decision, an example of Tannehill trying to force something when nothing was there. That play came on a first-and-goal from the 7, so after Tannehill rolled out, the right move clearly was to just throw the ball out of bounds.
But that play will pale in comparison with what Tannehill accomplish in that fourth quarter.
Not only did he lead the game-winning drive, Tannehill twice led long touchdown drives to erase seven-point deficits.
Remember, after Daniel Thomas scored from 3 yards out following the interception erased by the penalty, Leon Washington returned the ensuing kickoff 98 yards for a touchdown, so the Dolphins again found themselves down by seven, this time at 21-14.
Miami's next drive started at its 20, but all it took was six plays for the Dolphins to tie the game again.
A Reggie Bush 22-yard run jump-started the drive, but Tannehill followed with an 18-yard completion to Thomas and then a beautiful 29-yard TD pass to tight end Charles Clay, who stepped up big time on Sunday with starter Anthony Fasano nursing a leg injury.
The Dolphins' final drive began at their 10 after Jared Odrick sacked Russell Wilson on third down near midfield and Tannehill wasted no time.
He first hit Davone Bess running across the middle with a 19-yard completion pass, and then had his 15-yard scramble. After a false start by Rishard Matthews, Tannehill connected again with Bess for 25 yards and the Dolphins already were in field goal range at the Seattle 36.
Tannehill has had days with more passing yardage or a higher passer rating this season, but this undoubtedly was the biggest game of the season for him.
It bears repeating: He took a major step against Seattle, one that we may one down look back on as a significant moment in his career.