Richard Sherman offers an explanation to Seahawks fans. (Jim Mone/Associated Press)

The reaction in Seattle, replete with the supposed torching of his No. 25 Seahawks jerseys, was enough to get Richard Sherman to open up about his motives for signing a three-year contract with the team’s hated rival.

“I’m vengeful that way . . . vengeful,” Sherman said in an interview with Peter King of the MMQB. “I love the [Seattle] fan base to death, and I loved playing there. It was such a great opportunity. I helped the organization get to a great place and stay there. But now it’s like I abandoned them. People are out there burning my jersey. Come on. I’m not the one who let me go. They let me go. I didn’t abandon anybody.”

He raises a fair point. The Seahawks released him and declined the opportunity to match the 49ers’ offer. Which means that the cornerback, who turns 30 on March 30 and is coming off Achilles’ surgery, will be extra motivated twice a year when the two teams meet, and by the fact that his three-year contract with the Niners is laden with incentives.

Monday afternoon, Sherman repeated his stance, tweeting: “Instead of getting upset with me for going to a new team, how about you get upset with the people who forced me to go? If one job fires you and another job offers you a great position, I highly doubt most people would go back to the old job for a lot less money.”

Sherman, who is from Los Angeles and attended Stanford, represented himself in negotiations.

“I don’t think any agent in the business could have done a better job of negotiating this contract,” Sherman told King. “As long as I’m content with what I’m making, nothing else matters to me.

“Once I make a Pro Bowl, $8 million the next year is guaranteed for me. It gives me the ability to control my destiny. The 49ers have skin in the game. I have skin in the game. In my former contract, no matter what I did this year, nothing would be guaranteed to me next year. I couldn’t feel secure in my contract. Now, if I play the way I know I’m capable of playing, I know I’m going to get paid.”

A four-time Pro Bowl selection, Sherman played in nine games last season, recording 35 tackles and two interceptions. As for that jersey burning (see it here, with NSFW language), it appears to have been fairly random, although it did gather a ton of attention.

Another fan took his rage to the road.

Thus, two fan bases are making some heady changes. The 49ers and Seahawks have had a fierce, bitter rivalry, one that has led to police putting undercover officers in 49ers gear during games in Seattle.

Sherman might be changing jerseys, but history is history. John Lynch, the 49ers’ general manager, admitted to King that San Francisco “had something no other team could offer” to Sherman: “The ability to play Seattle twice a year.”

It’s on.

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