Now, stunningly, he's out as New York's general manager.
Team chairman and CEO Christopher Johnson announced the decision to fire Maccagnan in a statement posted Wednesday on the team's Twitter account.
"It was a decision that evolved," Johnson said during a conference call a few hours after the announcement. "And it took a while and maybe I was slow with that decision, but I finally came to it in the last few days."
Coach Adam Gase will serve as the acting general manager while the Jets search for a replacement. He wasted no time in his new role, trading linebacker Darron Lee to Kansas City for a sixth-round draft pick, pending a physical, according to two people with direct knowledge of the deal. The people spoke to The Associated Press on condition of anonymity because neither team had announced the move late Wednesday night.
ESPN reported that Brian Heimerdinger, the Jets' vice president of player personnel, also was fired.
Maccagnan had long been on the hot seat, so the move itself isn't necessarily a shocker. The timing, however, is particularly surprising because Maccagnan ran the Jets' draft less than three weeks ago, including taking defensive tackle Quinnen Williams with the No. 3 overall pick.
"There's never a good time to make a decision like this, honestly," Johnson said. "But it's a process."
That included Johnson deciding to "get deeply embedded" in the organization's football operations by taking what he called a "deeper dive" this offseason.
"I was part of a lot of discussions about the free agents and sat in on dozens of interviews with the guys at the combine and sat in on scouting meetings and watched this process," Johnson said. "I understood more fully Mike's role in this building and what I'm hoping for in our future GM."
Johnson emphasized he wants "a strategic thinker" and added that "it's more than a talent evaluation guy." He also said he wants "a great manager, a communicator - someone who can collaborate well with the building."
There were reports during the last several weeks that there was tension between Maccagnan and Gase - which both denied.
"This had nothing to do with Adam," Johnson insisted. "I mean, I want good give-and-take between our GM and the coach. This was not one person or another winning a power struggle. This was completely my decision."
Maccagnan, who was hired as GM in 2015, had two years remaining on his contract after getting an extension at the end of the 2017 season. He was not relieved of his duties this past offseason when coach Todd Bowles was fired - leading many to assume that Maccagnan's job was not in immediate jeopardy.
"The more I looked, the more I realized that I wanted to move on," Johnson said while refusing to go into specifics.
Maccagnan was fully involved in the coaching search and hiring of Gase. He also was active in free agency, spending more than $125 million to land the likes of running back Le'Veon Bell , linebacker C.J. Mosley and wide receiver Jamison Crowder. He also acquired left guard Kelechi Osemele from Oakland in a trade.
The Jets also have what they believe is a franchise quarterback in Sam Darnold, who was the third overall pick in last year's draft after Maccagnan engineered a deal with Indianapolis to move up from the No. 6 spot. Safety Jamal Adams and defensive lineman Leonard Williams are also recent draft picks by Maccagnan who have become building blocks for the defense. Starting wide receiver Robby Anderson was also a terrific find as an undrafted free agent in 2016.
But Maccagnan's draft history since coming to New York after 15 years in various scouting positions with the Houston Texans is otherwise shaky, at best.
Only 11 of the 22 players selected in his first three years are still on New York's roster. The first-rounders have been starters - Adams (2017), Lee (2016) and Williams (2015) - but Lee became expendable with the Jets having Mosley and Avery Williamson at the inside linebacker spots.
Several other early round picks have been busts. Second-rounders Devin Smith (2015) and Christian Hackenberg (2016), and third-rounders Lorenzo Mauldin (2015) and ArDarius Stewart (2017) are all out of the league.
And now, the Jets will move forward with someone else making the personnel decisions. Johnson said Gase will "assist" in the search.
Eagles vice president of player personnel Joe Douglas is believed to be a primary candidate to replace Maccagnan. Douglas and Gase have a previous working relationship: Douglas was Chicago's director of college scouting in 2015, when Gase was the Bears' offensive coordinator.
In the meantime, Gase will oversee all roster moves as the Jets enter the next phase of the offseason with organized team activities set to begin next week. During his three seasons as coach of the Dolphins, Gase had final say on personnel decisions. He'll now have the same authority with the Jets - at least until they hire a general manager.
When he was introduced as New York's coach in January, Gase downplayed his power, saying it was "just kind of how it worked out in Miami" and that he "didn't even ask" for a similar setup when the Jets hired him.
In New York, the coach and general manager report directly to Johnson, a unique structure in the NFL. Most teams have the coach report directly to the GM, who then reports to the owner. Johnson, however, has insisted that that's the structure he believes works best and will remain in place when the Jets hire Maccagnan's replacement.
Under Maccagnan, the Jets were 24-40 with no playoff appearances in four seasons. The team's only winning season in that span came in the first year for Maccagnan and Bowles in 2015, when New York was 10-6 but fell a win short of making the postseason.
"I think that by diving deep in the organization, I had a better idea of what was wrong and where I wanted to head with this," Johnson said. "This is a long-term plan. We're trying to win football games. And, I just felt we had to have a new GM to help us do that."
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