Barely 24 hours after Sandy Alderson’s contract with the Mets expired last October, he got a surprise phone call from his past. It was Billy Beane, a former disciple of Alderson’s in Oakland and now an industry giant as the A’s vice president for baseball operations. Beane wasn’t interested in small talk, and he began the conversation with a pointed question:

“Do you want to come work for the A’s?”

Alderson was surprised and flattered, but he still hesitated. A recurrence of cancer hastened his decision to step away from his day-to-day duties as the Mets’ general manager last summer. Many in baseball assumed that Alderson, closing in on his 71st birthday, would simply retire — safeguarding his health and spending time with his family.

Yet Alderson found Beane’s offer intriguing: Alderson was, after all, Oakland’s general manager from 1983 to 1997, and he helped construct the so-called Bash Brothers club that won the World Series in 1989. Within days of Beane’s call, Alderson agreed to return to his roots in the Bay Area and work for his onetime protégé. The pair that had helped launch the sabermetrics revolution was reunited.

Alderson’s decision was driven by two factors. The first was his cancer-free status. Although Alderson has never disclosed what form of the disease he had, his scans have nevertheless been clean for several months. The second was Alderson’s desire to end his career on a more positive note — in the final two seasons of his eight-year tenure with the Mets, the team finished a total of 30 games under .500.

Whether Alderson had been forced out by Mets ownership or had grown tired of the job remains unanswered — in a recent interview he declined to address any of the behind-the-scenes issues or any of the struggles that his replacement, Brodie Van Wagenen, had encountered in his short tenure with the Mets.