Rivera, who has talked with eight NFL teams about their head coaching positions over the last two seasons, had a three-year contract with the Bears that was set to expire next week.
After it was announced he wouldn't be coming back to the Bears, Rivera vowed he would land another job.
And he did, getting a deal to join new Chargers coach Norv Turner. Rivera had just interviewed for San Diego's head coaching job last weekend.
"It's just time to move on again, so I will move on and I will prosper. I will bounce back. I will get an opportunity," Rivera said during a conference call before his Chargers' job was announced.
But the decision by Bears coach Lovie Smith not to keep Rivera came as a surprise to many, especially the timing _ a little more than two weeks since the Bears lost the Super Bowl. Rivera said he never started talks on a new contract with Chicago.
"It's just something that Coach decided he was going to shuffle his staff and we'll go from there," Rivera said.
Rivera said he wanted to return and was told a few days ago he wouldn't.
Was there a personality conflict with Smith?
"No, no, no, no, please. I don't think there is. I really don't," he said.
"I believe this is just a football decision and it was made. Emotionally, I'm disappointed in not getting the opportunity to come back in '07 because as I said at the end of the year after the loss that this is a football team that's headed in the right direction."
Smith, a defensive-oriented coach, insisted there no philosophical differences with Rivera.
"As much as anything, it's just a fit that we have and right now the direction I would like to go and the direction that Ron would like to go, we're going in two different directions," Smith said during a conference call.
"It's been my goal all along to help Ron, to do everything I could to get Ron an opportunity to get a head football coaching job and it's no more than that. We've tried to do that. Ron had a contract. I don't see it as a firing or anything like that. His contract expired and he wants to go in one direction, and I'd like to go in one. No more than that."
Rivera was a linebacker on Chicago's Super Bowl champion team in 1986 and then led a defense that helped the Bears make the playoffs in back-to-back seasons. Chicago had trouble containing Indianapolis in the Super Bowl, losing 29-17 to the Peyton Manning-led Indianapolis Colts.
Rivera has been an assistant coach for 10 years in the NFL beginning as a quality control coach with the Bears in 1997. He spent five years with the Philadelphia Eagles as their linebackers coach and the last three in charge of Chicago's defense.
The Bears led the NFL with 44 takeaways in the regular season, but the defense was slowed in the latter stages of the season after injuries to defensive tackle Tommie Harris and safety Mike Brown.
Smith didn't elaborate when asked if there were things about Rivera's performance he did not like.
"Those are the things Ron and I talked about," Smith said. "We feel good about the things we did together during that time, but no more needs to be said about that. That's between he and I."
Rivera was a candidate last season for head coaching jobs in Green Bay and St. Louis. This year he talked with Pittsburgh, Miami, Atlanta and Arizona before the Bears started postseason play. After Chicago lost the Super Bowl, he interviewed for coaching vacancies at Dallas and with the Chargers.
Smith, who has a year left on his contract and could be in line for an extension, said he would move quickly to replace Rivera. Linebackers coach Bob Babich is considered a top candidate.