Young met with Red Sox general manager Theo Epstein on Monday night in Arizona, the source said.
Young would appear to fit the profile of what the Sox are seeking in a replacement for John Farrell. Manager Terry Francona was with Oakland as bench coach in 2003, when Young was a minor league pitching coach and was promoted to the big leagues as pitching coach just days after Francona was hired as Red Sox manager. Francona's familiarity with Farrell as a former teammate and from working together in the front office in Cleveland was a big factor in Farrell's hiring by the Red Sox prior to the 2007 season.
Farrell was announced as the new manager of the Blue Jays on Monday.
While signs point to Young as the front-runner, a source said the Red Sox plan on interviewing other candidates as well before making a final decision. However, Young may know something others don't as he has informed people around him that he is taking the job with the Red Sox, sources told ESPN The Magazine's Buster Olney on Monday.
Young, 50, served under two managers in Oakland, Ken Macha and Bob Geren, and compiled an impressive resume. Despite having the youngest staff in the league in 2010 (average age: 26), the Athletics finished first in the AL with a 3.58 ERA. In Young's seven seasons, the Athletics finished lower than fourth in ERA just once. Oakland's home ballpark and its huge foul territory is a factor, but the Athletics still finished first this past season in ERA-plus, a statistic adjusted to home field.
Mark Mulder, Tim Hudson, Justin Duchscherer, Barry Zito, Dan Haren, Andrew Bailey and Trevor Cahill have all been All-Stars during Young's tenure, with Bailey winning AL Rookie of the Year in 2009 as the team's closer. Right-hander Cahill (fourth) and left-hander Gio Gonzalez (eighth) finished in the top 10 in ERA and won 18 and 15 games, respectively.
Young, who has been with the Athletics as a player or coach for the better part of 27 years, left of his own volition, turning down what was termed a substantial raise. The Athletics offered only a one-year deal, however, which may have been a factor. Geren has just one year left on his contract.
"This came as a complete shock," Oakland pitcher Dallas Braden, who threw a perfect game last season, told the San Francisco Chronicle. "He's been that accessible, everyone's favorite-uncle figure, a guiding light for us. He taught me how to study within the game, what to look for. He always understood my role and put me in the best position to succeed."
Other candidates on the Red Sox's radar include Mike Cather, who was Portland's pitching coach for three seasons (2007-09) before becoming a major league advance scout for the Sox this past season. Cather, who turns 40 on Dec. 17, is highly regarded by the team, but one club source questioned whether he is ready.
Gordon Edes covers the Red Sox for ESPNBoston.com. Buster Olney is a senior baseball writer for ESPN The Magazine.