The Denver Broncos and defensive coordinator Mike Nolan have agreed to part ways.

Nolan becomes the third member of coach Josh McDaniels' first staff to depart following a disappointing 8-8 finish. Offensive line coach Rick Dennison left for Houston's staff and running backs coach Bobby Turner was reunited with Mike Shanahan in Washington.

Dennison and Turner were both longtime holdovers from the Shanahan era. While their departures were expected, Nolan's comes as sort of a surprise.

Nolan, who engineered the Broncos' switch to a 3-4 defensive alignment, was McDaniels' first hire. McDaniels lined up Nolan to help revamp what had been a deplorable defense.

"I have great respect for Mike and wish him success in the future," McDaniels said in a statement released Monday by the team.

The reason for the split is a mystery. The Denver Post quoted Nolan as saying, "I can't say anything other than Josh and I mutually agreed to part ways."

Fox Sports was one of the first to report the news of Nolan's departure.

The Broncos started the season 6-0 and were the talk of the league. Nolan received much of the credit as he turned around a defense that ranked near the bottom of the league in every major category in 2008.

Then the team went into a free fall, losing eight of their next 10 games to miss the postseason for a fourth straight year.

Now, the Broncos will be searching for their fifth defensive coordinator in five seasons.

After getting fired as head coach of the San Francisco 49ers in 2008, Nolan tried his hand in broadcasting but found himself wanting to return to coaching.

Then McDaniels came calling, offering him a chance to turn around the Broncos' defense that had slid under Shanahan's watch.

Known as a defensive wizard, Nolan jumped at the challenge.

He holed up in his office last offseason as he installed a new look and shuffled around personnel.

Denver gave him the pieces, bringing in perennial Pro Bowler Brian Dawkins to serve as a leader and add a swagger that had been missing. Dawkins sparked the Broncos.

One of the biggest beneficiaries of Nolan's system was Elvis Dumervil, who was able to use his long arms and low center of gravity off the edge of the line as a hybrid defensive end/linebacker. Dumervil turned in a Pro Bowl season as he finished with an NFL-leading and team-record 17 sacks.

Once again, though, Dumervil and his defensive teammates will be under a new defensive boss.

Dumervil will be a restricted a free agent if there's no collective bargaining agreement. Come next season, he will be working for his eighth defensive coordinator in eight seasons, including three at the University of Louisville.

AP Sports Writer Arnie Stapleton contributed to this story.

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