Bobby April made it official Tuesday: He's not part of the Buffalo Bills' future.

April ended an outstanding six-year run as the Bills' special teams coordinator by exercising an option in his contract that allowed him to leave the team.

All of the Bills' assistant coaches are free to leave, and all of them will be gone unless the Bills' new head coach decides he has a spot for them on his staff. April, however, decided he did not want to wait around to see if the new head coach would be interested in him.

"I wanted clarity so everyone else in the league would know where I stood," April said. "There could be an assumption that I'm here until the new head coach decides if I'm here, and that's not the case."

April joined the Bills in 2004 and has held the added title of assistant head coach since 2006.

The fact the Bills were not going to interview him for their head-coaching position evidently caused April to

decide it was time to go elsewhere.

Asked if that was a big factor in his decision, April said: "It's been my goal, and I've worked diligently for about 20 years to be a head coach. So I'll let that be my answer."

The move was not a surprise, since the Bills are overhauling their football operation.

April stressed he leaves on good terms with the Bills' organization.

"I've got no beef with anybody," April said. "My tenure here is over. It's not over because of any angst on my part. And I've got a great rapport with the people here. I came up in the South as a defensive high school coach and Buddy Nix was a well-regarded defensive coach. I followed his whole path, his career. I have great respect for him. Jim Overdorf has been nothing but fair to me. Mr. [Ralph] Wilson has directly or indirectly put a lot of my kids through school the last six years. I've got no gripe.

"I can tell you in all sincerity that there is no such thing as a bad day in coaching, only different kinds of good days."

April had two years left on his contract but a year ago inserted a clause in the deal that gave him the right to opt out, which is what he did.

April, 56, coordinated the best six-year stretch of special teams play in Bills history and perhaps the best stretch in NFL history.

The Bills finished No. 1 in the NFL in overall special-teams performance in 2004, 2005 and 2008, according to rankings by the Dallas Morning News, which are recognized by special teams coaches as the league standard.

"It's unprecedented. I think we'll finish inside the top five again this year, which would make six years in a row [in the top five] and three of them No. 1," April said. "We were the first to finish No. 1 two years in a row. These guys have done a tremendous job. I'm pretty much the same coach as when I got here. I leave a much higher esteemed coach, and it's because of a lot of people's efforts.

"You can go all the way back to Gregg Williams and Tom Donahoe. When I got here, I didn't create that 2004 and 2005 team. It was already created. It continued with wise and sage decision-making in terms of the type of person we needed [to play special teams]. You need a certain type of person to do that area. You've got to make good judgments. The organization did make good judgments. I'm thankful to have a run like this again in my coaching career."

The Bills almost pulled off the mythical "Grand Slam of Special Teams" in 2005, coming close to No. 1 in all four main coverage and return categories. That year they were No. 1 in kickoff return average, No. 5 in punt return average, No. 4 in kickoff coverage and No. 1 in net punting.

In 2004, they were No. 2 in kickoff return average, No. 5 in punt returns, No. 2 in kickoff coverage and No. 11 in net punting.

The Bills' average drive start after kickoffs in 2004 (the 34.5-yard line) was the best total of any team this decade.

The Bills ranked among the top 10 in kickoff coverage each of April's six years at the helm (based on kickoff return average by opponents). Buffalo had two costly return turnovers this season, by Leodis McKelvin at New England and by Roscoe Parrish versus Cleveland. But the Bills still ranked among the top 10 in kickoff returns, net punting and kickoff coverage.

Punter Brian Moorman had his best year this season, setting a team record with a net average of 40.2 yards per kick.

"Brian reached a really landmark achievement — a 40-yard net average," April said. "Until two years ago no one in the league had ever done it. He did it with an unbelievably complex and diverse number of people playing on that punt team. It's a tribute to all those players, but it's a greater tribute to Brian."