PHOENIX -Red Sox assistant general manager Josh Byrnes was hired Friday as general manager of the Arizona Diamondbacks.

The 35-year-old Byrnes replaces Joe Garagiola Jr., who resigned to become senior vice president of baseball operations in the commissioner’s office.

Byrnes, known for his elaborate statistical analysis of the game and its players, had been assistant GM of the Red Sox since Epstein was hired as general manager in 2002. The two worked together to develop the Boston team that won the World Series championship in 2004.

Byrnes was scouting director of the Cleveland Indians before serving as assistant general manager of the Colorado Rockies for three years.

The Diamondbacks interviewed several candidates, including San Diego Padres general manager Kevin Towers, Chicago White Sox director of player development Dave Wilder, Washington Nationals general manager Jim Bowden and Diamondbacks interim GM Bob Gebhard.

Byrnes is not the youngest general manager in the game, however. The Texas Rangers recently promoted Jon Daniels, 28, to the post, part of a trend toward young general managers.

Byrnes will work with former agent Jeff Moorad, a Diamondbacks general partner, in making personnel decisions for a team that went 77-85 last season, below expectations but a significant improvement from the 2004 squad that lost 111 games.

At the top of the list will be improving a bullpen that was one of the worst in baseball for most of the season.

The team has fired pitching coach Mark Davis and replaced him with longtime Seattle Mariners pitching coach Bryan Price.

AP-ES-10-28-05 1339EDT