From the first day Mike Mularkey became interim head coach of the Tennessee Titans in November 2015, he vowed to protect franchise quarterback Marcus Mariota. It was a smart strategy—playing a young quarterback behind a terrible offensive line is a surefire way for him to develop bad habits, get injured, or both. So the Titans beefed up their protection, drafting Jack Conklin with the eighth overall pick in 2016 to pair with Taylor Lewan, the 11th overall pick from the 2014 draft, to form one of the top offensive tackle combos in the NFL. Mariota was sacked 23 times in 2016, tied for seventh lowest out of the 32 quarterbacks who started seven or more games that year. Behind that line, Mariota looked like a future star, and DeMarco Murray and Derrick Henry led a Titans ground attack that finished with the third-most rushing yards in the league. With the former no. 2 overall draft pick breaking through, an elite offensive line in place, and a talented running game supporting Mariota, Tennessee entered 2017 as the NFL’s sleeper du jour.

The Titans fulfilled that potential––sort of. They made the playoffs, but looked like one of the weakest teams in this year’s field heading into their wild-card matchup against Kansas City, and rumors swirled that Mularkey would be fired if the Titans lost the game. Tennessee trailed 21-3 at halftime of that game but went on to make an incredible comeback, beating the Chiefs 22-21. That win earned Mularkey a vote of confidence from Titans controlling owner Amy Strunk, who said Mularkey would remain the Titans coach “moving forward.”

But that didn’t last long. Tennessee was throttled by New England in Saturday’s divisional round game, losing 35-14, and the team announced Monday that it had “parted ways with head coach Mike Mularkey after the two parties couldn’t come to an agreement over the future.”

Titans part ways with head coach Mike Mularkey. Read: https://t.co/9R7Q0DKjBP pic.twitter.com/vu5Z6bD6Kr — Tennessee Titans (@Titans) January 15, 2018

In a post on the team’s website, senior editor Jim Wyatt wrote that “questions about the development of quarterback Marcus Mariota and the team’s inconsistent offense were persistent throughout the course of the season.”

As The Ringer’s Danny Kelly wrote on Saturday, the run-heavy “exotic smashmouth” offense Mularkey originally installed to protect Mariota may have stunted the quarterback’s growth. The Titans used a compressed offensive scheme—the opposite of what Mariota played in at Oregon—that often featured two- and three-tight-end sets, and infrequently used play-action despite Mariota being one of the best play-action passers in the league this season. Mariota threw 13 touchdowns and 15 interceptions in 2017 after tossing 26 touchdowns and just nine picks the year before, and at times made throws that were either poor reads or just plain terrible:

Mariota's season from Hell continues, while Goff nails a deep pass to Cooper Kupp. pic.twitter.com/IIfutgXsnh — Ian Wharton (@NFLFilmStudy) December 24, 2017

Mularkey’s unimaginative scheme affected the offense’s production overall. Tennessee’s passing attack dropped from ninth in DVOA in 2016 to 20th this season, and the running game went from third in the league in rushing yards to 15th. General manager Jon Robinson drafted wide receiver Corey Davis fifth overall in the 2017 draft and added Eric Decker in free agency, but they finished with just 375 and 563 receiving yards, respectively.

Mariota is already the unquestioned leader in Tennessee, and his development trumps everything else. Robinson is considered one of the sharpest executives in the league, and he’s put together a fantastic young core in Nashville, but now he needs a head coach to develop that core within a modern offense. Patriots offensive coordinator Josh McDaniels is considered a leading candidate, and he overlapped with Robinson in New England.

Whoever the Titans hire, they’ll almost certainly institute an offense that’s more conducive to Mariota’s skill set. Mularkey nearly saved his job with the comeback win against the Chiefs, but one good half of football doesn’t erase two-plus years of trying to fit players into a scheme rather than adapting a scheme to the strengths of the players.