Let the offseason begin. The celebratory bubbly barely had time to dry last night in St. Louis when the free agent field started taking shape. For the next five days, eligible players may negotiate only with their most recent team. By Thursday, though, the overwhelming majority will be free to seek offers from other clubs. Jonathan Papelbon has been waiting for this moment. The Red Sox closer has long stated his willingness to pitch under a string of one-year contracts, risking injury and other depreciation to his value, until he reached free agency. Now, at age 31 (next month) and coming off a dominating season, he's finally able to test his worth on the open market. If the Red Sox ever were resigned to letting Papelbon walk, they aren't any longer. Not after closer-in-waiting Daniel Bard posted a 6.95 ERA in August and September, and Bobby Jenks suffered a series of health problems that limited him to only 19 appearances and may threaten his readiness for spring training. Papelbon, meanwhile, struck out 12.2 batters per nine innings, his highest total since 2007. His strikeout-to-walk ratio rose to 8.70, the best it has been since 2008. He posted a 2.94 ERA, went 31-of-34 in save situations and matured into a clubhouse leader, according to former general manager Theo Epstein.