Theo Epstein, John Henry Make Adrian Gonzalez Trade Official for Red Sox

Adrian Gonzalez is officially a member of the Boston Red Sox. General manager Theo Epstein made the announcement with principal owner John Henry at a Fenway Park news conference on Monday.

The first baseman arrives from San Diego in exchange for three of the Red Sox’ top prospects — Single-A outfielder Reymond Fuentes, Double-A pitcher Casey Kelly and Double-A first baseman Anthony Rizzo — and a player to be named later.

“I’m very excited to be here in Boston and ready to beat the Yankees,” Gonzalez said at the news conference.

Gonzalez hit .298, with 33 doubles, 31 home runs, 101 RBIs and 87 runs scored to go with 93 walks in 160 games in 2010. The lefty was named the Padres’ Most Valuable Player for the fourth time in 2010.

“I’ve had five incredible years in San Diego and grew up wanted to be a Padre, and my dream as a kid was to play in the major leagues and be a Padre,” Gonzalez said. “And my second dream was to be a Red Sox.”

Gonzalez has at least 30 home runs in each of the past four seasons and leads all MLB first basemen in games played (792), games started (779) and innings played (6,978) since 2006.

Although the Red Sox and Gonzalez could not come to terms on an extended contract, the team traded for him as a sign of good faith.

“We got close to a deal, but in the end when the window lapsed and we didn’t have a deal, we decided to go forward with the trade anyways as a demonstration of the good faith that developed,” Epstein said. “Had we not gotten to know Adrian and his wife and what they were all about over the course of the weekend, we wouldn’t have had that comfort.

“It’s just such a good fit. Adrian wants to be a Red Sox. We want him to be a Red Sox for a long time. We’re very confident that when the time is right, we’ll be able to work something out.”

With the addition of Gonzalez, the Red Sox’ 40-man roster now sits at 38 players.