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Do you remember Marcus Mariota Fever?

It swept across the NFL just three years ago. Mariota had just won the Heisman and every other college football trophy you could name, and the whole league wanted a piece of him.

Chip Kelly, Mariota's former college head coach turned Eagles imperial overlord, wanted to trade everything but the the keys to Independence Hall for the right to draft Mariota. The Browns offered a pair of first-round picks for the opportunity. Fanbases around the league clamored for the Oregon superstar, But the Titans held firm with the second overall pick and anointed Mariota their quarterback of the present and future.

Mariota then threw four touchdown passes in his NFL debut, easily outdueling Jameis Winston, the quarterback selected ahead of him in the draft, and added two more touchdown throws in his second start.

Pumped about Patrick Mahomes? Bonkers for Baker Mayfield? Psyched for Sam Darnold? That's how we felt about Mariota just 36 months ago.

Fast-forward to Sunday, when Mariota was sacked 11 times in a shutout loss to the Ravens. He completed just 10 passes for 117 yards, leaving the Titans with just 51 net yards after subtracting the yardage lost in sacks. For the second week in a row and third time in four games, the Titans were held without an offensive touchdown.

Mariota's early-season struggles could be attributed to injuries (to himself and teammates like favorite target Delanie Walker) if they weren't a continuation of a slump that began last year. Mariota is no longer part of the rising-star quarterback conversation. He's barely a topic of any conversation these days.

So whatever happened to the NFL's Next Big Thing?

The Injuries

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Mariota is playing with an elbow he injured in the season opener against the Dolphins. Mariota said he couldn't feel his fingers after the game, but he tried to hang in there, throwing a pair of interceptions before finally giving way to backup Blaine Gabbert in what became a 27-20 loss.

Gabbert, with the help of a fake punt and a healthy serving of Wildcat plays, engineered a 20-17 win over the Texans in relief of Mariota in Week 2. Mariota appeared to be barely capable of throwing downfield when he returned for a 9-6 win over the Jaguars.

Titans coach Mike Vrabel said after the Jaguars game that there were throws Mariota still could not make because of the injury. The quarterback didn't look very limited when throwing for 344 yards in a 26-23 win over the Eagles in Week 4, but he has been reluctant to take shots downfield since then, and some of the shots he has taken have been off-target and-or ill-advised.

Injuries have slowed Mariota throughout his career. His hot rookie start cooled off when he missed two games with an MCL sprain in October 2015. Another MCL injury ended his inaugural season in December. A broken fibula ended his 2016 season in Week 16. Mariota dealt with a litany of aches and pains last year: a hamstring injury that forced him to miss a start; a sprained quad in the playoff loss to the Patriots; minor shoulder, ankle and knee injuries in between.

The Mariota we've seen for the last two seasons has often been a Mariota who cannot run at full speed or properly grip a football.

But injuries alone have not turned the NFL's former Next Big Thing into just another guy.

The Systems

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Mariota enjoyed his greatest success in 2016 with a scheme former head coach Mike Mularkey dubbed "exotic smashmouth." It was a run-heavy offense full of option concepts: like a cross between Mariota's Oregon offense (without the uptempo component) and something you'd expect to see at a Texas high school in the 1960s.

Mariota threw for 3,426 yards and 26 touchdowns and ran for 349 yards as the Titans ground out victories by 13-10 and 19-17 scores.

But the 2017 version of Mularkey's smashmouth was far less exotic. Mariota threw just 13 touchdowns to 15 interceptions last year as opponents caught on to the Titans' tactics.

In a league where most successful teams spread the field so playmakers can operate in open space—a strategy tailored to the strengths of spread-option college quarterbacks like Mariota—Mularkey constricted the field and limited his quarterback to short throws between the numbers.

The Titans rode a soft schedule into the postseason last year, but Mularkey was fired in favor of Vrabel, Mariota's third head coach in four seasons, (Mularkey replaced Ken Whisenhunt during Mariota's rookie year.) Vrabel, a defensive coach, installed inexperienced Matt LaFleur as offensive coordinator.

LaFleur has Shanahan clan and Sean McVay ties, so his bona fides are in order. He's been forced to scheme around a quarterback who couldn't feel his fingers and Blaine Gabbert. He's faced some of the league's toughest defenses so far this year. And he made the Eagles defense look silly when it mattered.

So let's not point any fingers at LaFleur. But the Titans offense still looks constricted and not-so-exotically smashmouth, and Mariota alternates between having nowhere to throw and looking reluctant to pull the trigger.

Then again, power running, option threatening and short passing may be the only choices for Mariota's coordinators.

The Limitations

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Mariota was never advertised to have Mahomes-level arm strength. Or Winston-level arm strength, which is why Winston was drafted ahead of him. Or Mayfield-level arm strength, or…you get the idea..

"When cutting it loose, ball tends to sail on him a bit," read his NFL Network predraft scouting report. "Arm strength is adequate but inconsistent to field side." Adequate was a common description of Mariota's arm, even among his ardent supporters: His release, mobility, accuracy and toughness were all outstanding, making his arm just good enough.

Three years later, Mariota has produced just 18 passing plays of 40-plus yards in 47 career games. For comparison's sake, Ben Roethlisberger has 45 40-plus pass plays in the same span; Aaron Rodgers and Ryan Fitzpatrick have each produced seven in this season alone.

Arm strength is famously overvalued, but it's also necessary. Mariota can put touch on the occasional deep ball, but it's rare to see him throw a rope to the deep sideline or into heavy traffic to stretch out a defense.

Coordinators may have spent three years shrinking the field for Mariota because they have no choice, especially when he's coping with this or that injury.

Whatever the root cause, Mariota has become caught in a vicious cycle. Those bunched-up offensive formations just bring defenders closer to the line, making blitzing easier and more effective, exacerbating the aches and pains that further limit his effectiveness, resulting in even more junior varsity offensive concepts, and so on.

It all bottomed out last Sunday, when the Titans often kept two extra blockers at home to protect Mariota, yet he still endured 11 sacks, in part because all the extra blockers left him with no one to throw to.

The Tough Decisions

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The Titans exercised the fifth-year option on Mariota's rookie contract prior to this season. He costs the team just under $8 million in cap space this year, but that figure rises to $20 million in cash next year.

That means decision time is looming for the Titans. Soon, they must either extend Mariota's deal or enter the risky world of letting him play out the option while keeping their own options open.

No one questions Mariota's dedication or determination. But no team can afford to hand out going-rate $25-million-per-year rewards for dedication and determination for quarterbacks who have been slowly backsliding for much of their career, no matter who or what's to blame for the disappointments.

Things might have been different if he landed with a spread-option guru instead of the NFL's old guard early in his career, or if he wasn't always playing through a nagging injury, or if he could add just five miles per hour to the fastball.

But right now, Mariota bears little resemblance to the player we saw three years ago, and the Titans have to figure out if he is still a starting-caliber quarterback at all.

"I remember it like it was yesterday, man," Eagles defensive tackle Fletcher Cox said of Mariota Fever leading up to the draft, per Zach Rosenblatt of NJ.com. Cox was mentioned in trade talks to move up to draft Mariota back then, so of course the memory remains fresh for him.

But for most those of us, the era when Mariota was a Mahomes-like phenomenon is a memory that's rapidly getting buried under piles of opposing defenders.

Mike Tanier covers the NFL for Bleacher Report. Follow him on Twitter: @MikeTanier.