MIAMI -- The first airborne banner calling for Jeff Ireland to be fired flew over the Miami Dolphins' stadium in 2011. Other similar signs followed, most recently in November, and on Tuesday those wanting him out finally got their wish.

Ireland's six-year stint as general manager ended with a brief announcement that he and owner Stephen Ross mutually agreed to part ways. The Dolphins said they would conduct an immediate search for a replacement to lead football operations.

A late-season flop kept Miami out of the playoffs for a fifth consecutive year, and Ireland has long been considered the main culprit for the franchise's failures. More than two dozen frustrated fans gathered outside the Dolphins' complex one spring day in 2012 to protest the way the team was being run, with some holding signs that read "FIRELAND."

He wasn't fired, but in the wake of last month's meltdown, Ross considered hiring a football czar over Ireland and coach Joe Philbin. Ireland was opposed to such an arrangement.

"Steve and I came to an agreement that the best thing moving forward for all parties would be to part ways," Ireland said in a statement. "I'd like to thank Steve for all his support and kindness. I've had the opportunity to work with some of the most amazing people during this time, and I'd like to thank them all from the bottom of my heart."

Ross said the decision regarding Ireland came after they had a series of discussions.

"We both felt that it was in our mutual best interest to part ways," Ross said in a statement. "Jeff was a loyal and dedicated member of the Dolphins and we wish him and his family nothing but the best."

Still to be determined is Ireland's role in a locker-room bullying scandal that drew national scrutiny. The NFL has yet to release a report on its investigation into the case.

Ireland's departure follows Monday's firing of offensive coordinator Mike Sherman. Philbin will return for a third season, but other changes in his staff are possible.

The Dolphins (8-8) would have made the playoffs if they had won one of their final two games against the Bills and Jets. Instead, they were beaten by a combined score of 39-7.

Ross spent more than $100 million in guaranteed money last offseason to upgrade the roster, and the investment delivered only slight improvement from a 7-9 record in 2012.

Ireland, a protege of Bill Parcells, was hired as general manager in 2008, and the Dolphins won the AFC East in his first season. But they haven't been above .500 since, the longest such stretch in franchise history.

Ireland's personnel decisions have produced mixed results. This season, $60 million newcomer Mike Wallace had a career-low five touchdown catches, but free-agent acquisition Brent Grimes made the Pro Bowl.

In 2012, Ireland drafted Ryan Tannehill, who shows signs of becoming the franchise quarterback Miami has sought since Dan Marino retired following the 1999 season. But Ireland's 2013 draft picks played the fewest snaps of any team in the NFL, including overall No. 3 choice Dion Jordan, who had only two sacks all year.