The Mets will be bringing back Jose Valentin, the player's agent told The Post last night, giving him a minor league deal with an invitation to major league spring training. Valentin, 38, was a huge contributor for the Mets in 2006, hitting .271 with 18 homers as their second baseman. But last year he played in only 51 games due to a partially torn ACL and a broken tibia. According to agent David Elston, Valentin is currently rehabbing his ACL (he had left replacement surgery on Sept. 25) and is unlikely to be doing baseball activities until mid-March. With a minor league pact, Valentin obviously is not guaranteed to make the club. But Elston said Valentine didn't consider retiring.