Philadelphia hired Kelly on Wednesday, just 10 days after he decided to stay at Oregon. The 49-year-old Kelly, known as an offensive innovator, becomes the 21st coach in team history and replaces Andy Reid, who was fired on Dec. 31 after a 4-12 season.

He’ll be introduced at a news conference Thursday at 1:30 p.m. at the Eagles’ practice facility.

Kelly, who was 46-7 in four years at Oregon, interviewed with the Eagles, Cleveland Browns and Buffalo Bills in a two-day span after leading the fast-flying Ducks to a victory over Kansas State in the Fiesta Bowl Jan. 3.

The Eagles are known to have interviewed 11 candidates, including two meetings with Seahawks defensive coordinator Gus Bradley. All along, Kelly was thought to be Philadelphia’s first choice in a long, exhaustive process that took many twists.

“Chip Kelly will be an outstanding head coach for the Eagles,” owner Jeffrey Lurie said in a statement. “He has a brilliant football mind. He motivates his team with his actions as well as his words. He will be a great leader for us and will bring a fresh energetic approach to our team.”

On the day he fired Reid, Lurie appeared to be describing Kelly when he said he wanted to find a “real smart, forward-thinking coach” who is “strategic, a strong leader, very comfortable in his own skin.”

The enigmatic Kelly reportedly was close to signing with the Browns after a long interview Jan. 4. He met with the Eagles for nine hours the next day, setting up a soap-opera scenario in which the Eagles were competing with Browns CEO Joe Banner, their former president and longtime friend of Lurie who left the organization after a falling out. But that roller coaster ended when Kelly opted to remain — temporarily — in Eugene, Ore.

“It’s a very difficult decision for me. It took me so long to make it just because the people here are special,” Kelly told KEZI-TV. “The challenge obviously is exciting for me, but it’s an exciting time and it’s a sad time — saying goodbye to people you love and respect, and I wanted to make sure I talked to my players and did it in the right fashion and talked to our staff. I feel I did.”

The Eagles interviewed two other high-profile college coaches — Penn State’s Bill O’Brien and Notre Dame’s Brian Kelly. Both of them elected to stay with their schools.

Bradley was considered by many to be the leading contender, though former Cardinals coach Ken Whisenhunt and former Ravens coach Brian Billick were in the mix.

That all changed when Kelly had a change of heart.

The visor-wearing Kelly built Oregon into a national powerhouse. The Ducks went to four straight BCS bowl games — including a bid for the national championship against Auburn two seasons ago — and have won three conference championships.

Kelly originally went to Oregon in 2007 as offensive coordinator under Mike Bellotti. Before that, he was offensive coordinator at New Hampshire, where he started devising the innovative hurry-up offense the Ducks are known for now.

Oregon finished last season 12-1. The team was ranked No. 1 and appeared headed for another shot at the national championship until a 17-14 loss to Stanford Nov. 17.

Ducks athletic director Rob Mullens said Wednesday that Kelly called him at 7:15 a.m. PST to tell him he had changed his mind: “He wasn’t sure if that opportunity would present itself again, so he felt this was the right one at the right time.”

Mullens now faces a coaching search amid recruiting season.

“I’ve turned the page,” Mullens said. “I was surprised when I got the call this morning, but as the leader of this organization, my focus is on moving forward and that’s what we’re doing. I’m laser focused on what’s next, and that’s finding the right fit to lead Oregon football.”

It’s unknown whether the possibility of NCAA sanctions based on Oregon’s use of recruiting services factored into Kelly’s reversal. He indicated in Arizona that he isn’t running from anything.

“We’ve cooperated fully with them,” he said. “If they want to talk to us again, we’ll continue to cooperate fully. I feel confident in the situation.”

Kelly doesn’t have any pro coaching experience, but aspects of his up-tempo offense are already being used by New England and Washington.

The Eagles fired Reid after two forgettable years. A late flurry brought the team to an 8-8 finish last season, but this season, Philadelphia endured an eight-game losing streak, and dropped 11 of its final 12. A 3-1 start soon washed away, and Reid’s 14-year tenure ended not long after. Within a week, Reid was Kansas City’s new coach.

Still, Kelly has tough shoes to fill. Reid won more games than any coach in franchise history and led the Eagles to nine playoff appearances, six division titles, five conference championship games and one Super Bowl berth.

Kelly and the Eagles have the No. 4 overall pick in the draft as well as some talented players on offense who could fit his up-tempo scheme. Running back LeSean McCoy and wide receivers DeSean Jackson and Jeremy Maclin seem like an ideal match. Quarterback Nick Foles, however, isn’t.

“I’ve never run the zone read,” Foles said after the season. “I’m more of a dropback guy. I’ve been under center. I’ve been in the gun. If I can adapt, I want to. But I’m not a zone-read quarterback. Some people are gifted with different things. That’s just not one of my skill sets. I can work on the speed in the offseason and get better with that. But I’ve always been a dropback guy in the pocket. I’ve been able to make plays on my feet throwing the ball or running for a first down.”

On the other hand, Michael Vick could be perfect. But it’s unlikely the Eagles would want to pay the $16 million they’d have to shell out for an injury-prone quarterback, who will be 33 next season.

Kelly had high praise for Foles after Oregon beat Arizona 56-31 in September 2011.

“I’ll tell you what; I’m glad Nick Foles is graduating,” Kelly said at that time. “I catch myself watching him in awe sometimes. Nick is a hell of a football player. That kid’s a warrior. He’s as good as anyone in the country.”

Others interviewed by Lurie, general Howie Roseman and president Don Smolenski were former Bears coach Lovie Smith, Atlanta assistants Mike Nolan and Keith Armstrong, former Broncos offensive coordinator Mike McCoy and Bengals offensive coordinator Jay Gruden.

The first Eagles to react to Kelly’s hiring on Twitter were defensive players.

Defensive end Brandon Graham wrote: “Happy to have Chip Kelly!! Now it’s time to get to work!”

Safety Kurt Coleman wrote: “Welcome Chip Kelly to the Eagles family. Can’t wait to see what he brings to the team in 2013!”

Oregon’s players gave Kelly a Gatorade bath at the end of his last game, and some seemed resigned to their coach moving on.

“We’re all behind him,” quarterback Marcus Mariota said. “He’s someone that you can look to and learn a lot of life lessons from. Whatever happens, happens. We’ll see where it takes us.”

Kelly took the road to Philadelphia and the NFL.