The Jets started the season 8-3 under quarterback Brett Favre, beating the Patriots and Tennessee on the road in consecutive weeks and raising visions among fans of the team's first Super Bowl trip since 1969.
But they went 1-4 in their final five games, losing to Denver, San Francisco, Seattle and Miami and barely beating Buffalo. They did not reach the post season for the second straight year despite an off0season spending spree that included a trade for Favre after his retirement and return at Green Bay.
The 39-year-old Favre had just two touchdown passes and nine interceptions in those final five games. He led the league in interceptions with 22 and complained after Sunday's 24-17 loss to Miami of pain in his right shoulder and neck.
The win gave the Dolphins the AFC East title under Chad Pennington, the Jets' longtime quarterback who was cut when the team obtained Favre.
The 37-year-old Mangini was called by owner Woody Johnson one of the league's up-and-coming coaches, but went 23-26 in three seasons in his first head-coaching job. He had another year remaining on his contract.
"For the current New York Jets organization, we've made the decision to move on," Johnson said at a news conference Monday. "It's a judgment call.
"I don't think it was one thing," he added. "We had to go in a different direction. There's nothing specific. It's just a call we made. Hopefully, it's correct."
As a rookie coach, Mangini took a team that had been 4-12 the previous year to the playoffs with a 10-6 record in 2006 and earned the nickname "Mangenius" from the local tabloids.
Johnson said the final decision was made Sunday night, but the process had been going on a long time. He met with the coach Monday morning.
"We thanked him for all the good things he had done for us," Johnson said. "We thanked him for his dedication and his loyalty. But he understood."
Jets general manager Mike Tannenbaum praised Mangini, saying he did not think he had lost the team.
"One way to answer that, if you look at the way the team played (Sunday) night, I thought they played hard," Tannenbaum said. "Saw a lot of guys running hard to the ball and I thought special teams, they played with a lot of energy."
The Jets, 4-12 a year ago, began the off-season by spending $140 million on veterans, notably offensive linemen Alan Faneca and Damien Woody and linebacker Calvin Pace. They also traded linebacker Jonathan Vilma, a young standout, because he did not fit Mangini's 3-4 scheme and traded for Kris Jenkins, a 350-pound defensive tackle with a history of back problems.
Jenkins was dominant early on but tailed off toward the end of the season, as did the rest of the defense.
Mangini: From Hartford to Pats to Jets
Mangini was born in Hartford and He attended Bulkeley High, where he received the Brian Piccolo Award for outstanding athletic and academic achievement and was named the Scholar Athlete of the Year as a senior, according to his biography on the New England Patriots Web site.
He attended Wesleyan and worked as an intern for the New England Crusaders, a minor league football team in Hartford.
In 1998, he received the scholar-athlete award from the National Football Foundation and College Hall of Fame, Northern Connecticut Chapter.
Mangini spent five years as the Patriots' defensive backs coach, then served as New England's defensive coordinator under Bill Belichick for a season before joining the Jets. He quickly became regarded as one of the game's top young coaching minds.
After the Jets traded the rights to coach Herm Edwards to the Kansas City Chiefs for a fourth-round pick in the 2006 draft, they replaced him with Mangini.
With a workmanlike and tight-lipped approach, Mangini drew instant comparisons to Belichick. And they appeared warranted, especially after a quick turnaround season.
When Mangini came to the Jets, it was believed Belichick was annoyed his young assistant left him, marking the beginning of a rift. There also was talk that Belichick was angry Mangini was speaking to Patriots players and coaches about joining him in New York. That was capped by New England filing a tampering charge against the Jets in connection with New York's trade talks with wide receiver Deion Branch. The Jets were cleared of the charges and Branch ended up in Seattle.
The dispute came to a head last year when the Jets reported the Patriots illegally used videotape to steal New York's defensive signals during the season opener. Belichick was fined $500,000 and the team docked $250,000 and a draft pick.
Still, Mangini couldn't lead the Jets out of the Patriots' shadow -- even with Tom Brady sidelined for the year -- and were surpassed in the division by the Miami Dolphins.
"He did a great job for us for three years and he helped lay a great foundation," Tannenbaum said. "We felt, in our judgment, we want to build on that and go in a different direction."