A-Gon: I’ve changed since Boston

Bobby Valentine told The Post this week that new Mets first baseman Adrian Gonzalez can be too opinionated and outspoken for some of his teammates, calling it “excessive.”

Gonzalez agreed, but insisted it was something that happened only during their disastrous season together in Boston in 2012.

“I think Bobby was in the right there,’’ Gonzalez said during a conference call Thursday after his deal with the Mets was finalized. “I think going into the 2012 season, I heard a lot of people telling me I had to be more of a vocal leader and do things that were out of [character] for me. I feel like I went into that season trying to make myself into something that I’m not used to doing. And I do agree with Bobby. I had a lot of opinions that year, but I don’t think it is who I am.”

He blamed the change on what happened at the end of the 2011 season, when the Red Sox suffered a September collapse under Terry Francona and missed the playoffs. That led to the departure of both Francona and general manager Theo Epstein.

The 2012 season wasn’t much better and in addition to Valentine being canned, Gonzalez was part of a salary-dump trade to the Dodgers that August.

“After the 2011 season, after things went downhill toward the end, there was a lot of pressure on the team going into 2012,’’ Gonzalez said. “I felt like I became a person that I didn’t want to be. ... When I was traded to L.A., I made a commitment to myself to not be somebody that somebody else wants me to be and just be who I am. I think that was the only season I’ve been that person and I promise that is not who I am, that’s not who I’ll be and it’s definitely not who I’m gonna be with the Mets.”

Instead, he is prepared to be the starting first baseman after talking with GM Sandy Alderson and new manager Mickey Callaway.

“Speaking to Sandy and Mickey, my role is first baseman of the team and to just be available off the bench in the games that I don’t start,” Gonzalez said. “There is somewhat of a defined role as far as starting a good amount of games, but it’s not set in stone. If my production is there, I assume I’m gonna be in the lineup.”

But Gonzalez added he’s ready to serve as a mentor to Dominic Smith, who could open the season with Triple-A Las Vegas.

“One of my big key points, especially in spring training, is to work with Dominic on defense and tell him about my experience to help him be the best major leaguer he can be in the future,” Gonzalez said. “And obviously doing everything I can to help us win games and get us in the playoffs and make a run like two years ago.”