From the Boston Herald’s Tony Massarotti.

According to baseball sources, current Red Sox assistant GM Josh Byrnes will be named the general manager of the Diamondbacks as soon as today. Byrnes, 34, joined the Red Sox staff shortly after Epstein became general manager following the 2002 season and has remained a confidant of Epstein ever since.

Byrnes (above, right) could not be reached for comment, but he likely will take over a Diamondbacks operation previously headed by former GM Joe Garagiola Jr. Garagiola left the team during the season to become the executive vice president for baseball operations at Major League Baseball, where he replaced Sandy Alderson, now CEO of the San Diego Padres.

Along with current Padres GM Kevin Towers, Byrnes was one of only two real candidates for the Arizona opening. Continuing what is a growing trend in baseball, the Diamondbacks opted for a promising, young executive with no previous experience as a GM. Earlier this month, following the departure of GM John Hart, the Texas Rangers similarly settled on 28-year-old Josh Daniels as Hart’s replacement.