It appears Mets general manager Sandy Alderson will soon be making an addition to his offseason to-do list: hire a new hitting coach. After getting passed over for the Mets’ managerial opening, hitting coach Kevin Long is not expected to rejoin the organization next season, a source told Newsday on Tuesday. Even after former Indians pitching coach Mickey Callaway was named manager, the Mets had hoped to retain Long as hitting coach. But his contract officially expired on Tuesday and it appears he’ll be on to his next stop. Long joined the Mets in 2015 as hitting coach, the same role he had filled with the Yankees from 2007 until his firing in 2014. His philosophies lined up with that of Alderson, a longtime believer in an ultra-disciplined plate approach that places an emphasis on selectivity and driving pitches for power. That shared philosophy — along with a strong reputation for communicating with players — is why Long was considered for the managerial opening. He had been one of six candidates interviewed for the job.