The NFL's highest-rated passer wasn't a starting NFL quarterback in the middle of October.

He leads the league in yards per attempt by a margin of more than a full yard, despite the fact that 46 quarterbacks—including 17 backups—are more highly paid than him, according to Spotrac. And he's now helped the oft-dull Tennessee Titans offense generate more than 30 points in four consecutive victories. 

The 31-year-old has never been to a Pro Bowl. He was cast aside this offseason by the objectively terrible Miami Dolphins. And his $2 million salary makes him only the 24th-highest-paid player (and the lowest-paid quarterback) on the Tennessee roster (incentives notwithstanding). 

That's about to change for Ryan Tannehill. 

The 2012 No. 8 overall pick was essentially written off as a bust after six not-dreadful-but-uninspiring seasons in Miami, and from a national perspective, the Titans' decision to acquire him to back up Marcus Mariota in 2019 was hardly newsworthy or consequential. Tennessee surrendered only a fourth-round pick in that deal, upgraded from a seventh-rounder to a sixth-rounder and then signed Tannehill to a cheap, incentive-laden one-year contract.

But now Tannehill, who took over as the team's starter for the ineffective Mariota in Week 7, is tearing it up to an extent that is impossible to ignore. 

If the season ended today, his 118.5 passer rating would be the fourth-highest qualified single-season mark in NFL history, and his trajectory indicates that could rise. 

He hasn't faced a lot of high-quality defenses of late, but the numbers go beyond the sort of inflation you might expect as a result of a soft schedule. 

During Tennessee's current four-game winning streak, Tannehill has nearly been perfect. He's completed 75.6 percent of his passes for over 1,000 yards, he's thrown nine touchdown passes to one interception and his passer rating is an astounding 144.2. 

He's just the third player in modern NFL history to post a passer rating of 130 or higher in four consecutive games. 

Tannehill was an afterthought from the top portion of the 2012 draft, mainly because top picks Andrew Luck and Robert Griffin III were the faces of that class. But neither is an NFL starter now, and it's time we give Tannehill credit. It's possible a lack of support at least partly explains why the frequently sacked Texas A&M product could never become a consistently successful starter for the Dolphins, and it's beginning to look as though Tannehill could be a late bloomer capable of picking up Luck's and Griffin's slack. 

Regardless, barring a catastrophic final stretch from Tannehill in 2019, somebody is going to pay the man this offseason. 

That somebody could very well be the Titans, who appear to be ready to move on from Mariota after five disappointing seasons. They basically added Tannehill as an insurance policy—a more appealing one than 2018 No. 2 Blaine Gabbert, who was released on the same day Tannehill was acquired. 

Now, ESPN's Dianna Russini reported on Sunday that the Titans "are internally discussing a new contract for" Tannehill. But his value has undoubtedly skyrocketed in the last two months, and it wouldn't be surprising if Tannehill decided to drive a hard bargain as potentially the hottest commodity on the 2020 quarterback market. 

If the price becomes too high in the coming weeks, the Titans very well could decide to make Tannehill prove it in a full season under the franchise tag. And that could happen if Tannehill and his representatives look at the supply-and-demand dynamics that could surround the quarterback carousel this offseason. 

The Cincinnati Bengals, Jacksonville Jaguars, Chicago Bears, Carolina Panthers, Tampa Bay Buccaneers, Indianapolis Colts, Los Angeles Chargers, Denver Broncos, Dolphins and even New England Patriots could be shopping for quarterbacks in the new year.

Even if Philip Rivers returns to the Chargers, Tom Brady returns to New England, Jameis Winston returns to Tampa, Cam Newton returns to Carolina and Mitchell Trubisky returns to Chicago, and even if Denver rolls with Drew Lock, Cincinnati drafts Joe Burrow, Indy gives Jacoby Brissett another shot and the Jags keep Nick Foles, there'll likely be market competition for Tannehill. The Dolphins could decide they made a mistake and try to bring him back, and a wild-card team like the Detroit Lions could even view him as an upgrade over Matthew Stafford. 

But it's likely to be an expansive market. There's a good chance that either Brady or Rivers (or Ben Roethlisberger) retires or moves on and an even better chance that Tampa Bay, Carolina, Chicago, Jacksonville or Indianapolis looks for somebody new.

This won't be like 2019, when only the Jaguars were really looking for a new quarterback and Foles was the obvious choice. He signed at a relative bargain as a result, but this is much less likely to be a buyer's market. 

Even if every potential 2020 free-agent quarterback were to hit the market, would any be more enticing than Tannehill? Rivers, Brady and Roethlisberger (who could theoretically be released) are declining rapidly and should only be viewed as short-term rentals right now. Foles and Brissett (both of whom are also under contract for 2020) have not looked remotely like franchise quarterbacks on fellow AFC South teams this season. Winston is a turnover machine. Trubisky (whose rookie deal runs through 2020) has been remarkably unreliable in his third season. Newton's recent struggles from a production and injury standpoint are terrifying (and his contract isn't about to expire either). It doesn't look as though Dak Prescott will escape Dallas.

And while Teddy Bridgewater won all five of his starts in place of Drew Brees earlier this season, the New Orleans Saints backup has his limitations as a passer. His 2019 statistics also pale in comparison to Tannehill's. 

Among quarterbacks who have attempted more than 15 deep passes in the last nine weeks, three have passer ratings of 120 or higher on those attempts: MVP front-runner Lamar Jackson, future Hall of Famer Aaron Rodgers and Ryan Tannehill. 

It helps that he finally has a quality offensive line, a top-notch running back and a stout defense. But he doesn't have established superstars at wide receiver, and yet he's making big-time throws every week. 

That's why even though he posted a 129.9 rating during a three-game hot streak in 2018 and three 120-plus ratings during a five-game run to close out the 2016 season, and even though his 2014 campaign was quietly rather superb, this stretch feels different. 

This has the feel of a strong player finally finding his best game in a new, more supportive environment. And while it would help Tannehill's cause if he finished off the season with robust performances against tough opponents (they play the Houston Texans twice and host the Saints), it would now be a tremendous upset if "that other quarterback" from the top 10 of the 2012 draft didn't enter 2020 as a stinkin' rich starter. 

Brad Gagnon has covered the NFL for Bleacher Report since 2012.