The Miami Dolphins fired Adam Gase after three seasons and will begin a search to find the franchise's fourth full-time coach this decade, the team announced Monday.

The Dolphins also promoted general manager Chris Grier to oversee football operations and reassigned Mike Tannenbaum, who had been executive vice president of football operations, within the organization.

Dolphins owner Stephen Ross said firing Gase was one of the hardest decisions he's ever had to make and that he didn't make the decision until Monday morning -- after deliberating the future of his team after Sunday's 42-17 loss to the Buffalo Bills.

"We've succeeded in everything except winning on the football field," Ross said. "Today, we're no further along than when I bought the team."

Gase couldn't escape the mediocrity that has followed the Dolphins since 2000. He finished 23-25, with his lone playoff game being a wild-card loss to the Pittsburgh Steelers in 2016. Miami was 7-9 this season.

Sources told ESPN's Jeff Darlington that trust between Gase and Ross had eroded in recent weeks -- and Gase had already rebuffed Ross' recent desire for him to give up control of the 53-man roster.

Ross mentioned several times that he wants to change the Dolphins' philosophy on building the team. He said he wants to get younger; Ross said Gase "wants to win now." And although Ross didn't say rebuild, it seems like the franchise is preparing to do that.

"We're going to build this organization based on our needs, and if it takes a year, two years, three years, we're going to be there," said Ross, who noted that going between 6-10 and 10-6 every year wasn't good enough. "I would hope I don't have to go 3-13, but whatever it's going to take."

Grier will have total control over football operations and report directly to Ross, who called him one of the "most respected people" in the NFL. Grier said he will begin his coaching search immediately and wouldn't rule out first-time head coaches or college coaches for the job.

The Dolphins have already requested interviews with Patriots defensive coordinator Brian Flores, Bears defensive coordinator Vic Fangio, Cowboys passing game coordinator/defensive backs coach Kris Richard, Steelers offensive line coach Mike Munchak and Chiefs offensive coordinator Eric Bieniemy for the vacancy, sources told ESPN.

"The ultimate goal is winning Super Bowls and being a consistent winner -- long sustained success where the fans are happy and Steve is happy," Grier said. "The important thing is finding the right guy who believes in some of the same things that I do, in terms of building a team. It's going to be a collaboration of everything we do still. It's not going to work if he and I don't share a vision to implement that plan throughout the organization."

Miami Vice The Dolphins, after firing Adam Gase, will be looking to hire their 10th head coach since the 2000 season. Coach Years Rec. Dave Wannstedt 2000-04 43-33* Jim Bates 2004 3-4 Nick Saban 2005-06 15-17 Cam Cameron 2007 1-15 Tony Sparano 2008-11 29-33* Todd Bowles 2011 2-1 Joe Philbin 2012-15 24-28 Dan Campbell 2015 5-7 Adam Gase 2016-18 23-26* 19 seasons 145-164* * Includes postseason

The biggest indictment of Gase was that he often fielded an anemic offense despite being thought of as an offensive guru and quarterback whisperer when he got the job. The Dolphins finished 24th or worse in total offense in all three seasons under Gase, including 31st in 2018.

In addition, he lost support in the locker room over the second half of the season. Three players told ESPN they felt Gase held some players, including quarterback Ryan Tannehill, to a different standard than others, and that alienated some on the team. Those players said they felt there wouldn't be a lot of hard feelings in the locker room if Gase was fired.

Ross had high hopes for Gase early on and said he believed he could become his Bill Belichick in Miami. But Gase could never duplicate the success he had in Denver, where he helped Peyton Manning lead the highest-scoring offense in NFL history.

Gase said prior to Sunday's loss to the Bills that he didn't "need to lobby for my job" and that if Ross "says there's an issue, I'll know."

Ultimately, Gase's biggest gripe with the 2018 season was with the health of his team, as he often said, "I wish everybody hadn't gotten hurt." He said he was hopeful Ross would understand the impact that injuries had on the season, citing the 13 players who ended the year on injured reserve -- many being key offensive contributors.

Winds Of Change With the impending hire of new head coaches for both the Dolphins and Jets, the AFC East will have had 27 coaches within the division since 2000 (including interim hires) entering play next season. Team Since '00 Bills 10 Dolphins 10* Jets 6* Patriots 1 * Including next head coach

Gase, 40, should receive opportunities this offseason to be an offensive coordinator and maybe even a head coach. This was Gase's first head-coaching job.

Within three hours of being fired in Miami, Gase already had heard from the majority of teams with a head coach vacancy, a source told ESPN's Adam Schefter. Sources told Darlington that Browns owner Jimmy Haslam, through a recommendation from Manning, is one of those teams with an interest in Gase.

Gase is expected to start interviews with those teams this week, a source told ESPN.

Fourth-quarter collapses at Indianapolis and Cincinnati, where questions about playcalling were apparent, also played a significant role in the Dolphins missing the playoffs. Miami had five games this season where it finished with fewer than 200 yards.

In the end, Gase tied himself to Tannehill and did not waver through rocky times. Tannehill's inability to stay healthy -- missing 24 games in Gase's three seasons -- and inconsistency hamstrung the Dolphins' offense and paved the way to Gase losing his job.

The Dolphins had three head coaches (George Wilson, Don Shula and Jimmy Johnson) over the franchise's first 34 seasons. Since Dave Wannstedt took over in 2000, however, the team has gone through nine head coaches, including interim coaches, and will be searching for a 10th.

The next Dolphins coach will likely get a chance to evaluate Tannehill and decide whether to select a quarterback high in April's draft, take a chance in a weak quarterback free-agent pool, make a big-splash trade or keep Tannehill.

Ross will be heavily involved in the Dolphins' coaching search, but he has told reporters that he would not have an interest in hiring Michigan coach Jim Harbaugh. Ross, a Michigan alumnus and significant booster of the school that named its business program after him, is known to have an affinity for both Jim and John Harbaugh.

The Baltimore Ravens said last week that John Harbaugh would return for the 2019 season and that they were working on an extension. Jim Harbaugh has said he is planning to remain with Wolverines.