The crosstown Yankees turned the baseball world upside down Saturday with their pursuit of slugger Giancarlo Stanton. The Mets — again working with a limited payroll — enter this week’s winter meetings with more modest goals. Bolstering the bullpen remains a top priority, sources told Newsday, as does exploring an intriguing trade market for second basemen. The Mets could use the winter meetings to initiate trade talks for Josh Harrison, who is coming off an All-Star season for the Pirates. Harrison brings the kind of defensive versatility the Mets covet. The Mets already have had trade talks for the Indians’ Jason Kipnis and the Tigers’ Ian Kinsler. Those discussions also could be revisited. Talks involving Kinsler are more advanced than discussions with the Indians about Kipnis, a source said, but another person with knowledge of the situation expressed skepticism about whether the Mets have a match with the Tigers. The Marlins might attempt to flip Starlin Castro, whom they would acquire from the Yankees once the Stanton trade becomes official. A source said the Mets would be unlikely to seriously pursue Castro, an indication that they prefer other options.