Sean Manaea’s time with the New York Mets could be coming to an end. Amid the Mets’ small turnaround in May, one major issue continues to plague the team: bullpen imbalance. The Mets currently carry three pitchers with nearly identical roles. Manaea, David Peterson , and Tobias Myers all work as multi-inning relievers. The Mets use them for extended outings, then rest them for several days. Carrying three long men has created several problems. When one of them struggles and exits early, the Mets often lack reliable relief behind him. Last night, after Freddy Peralta exited following five innings, Tobias Myers failed to escape the sixth. That forced the Mets to turn to trusted relievers Brooks Raley and Luke Weaver. After extending their lead to six runs in the ninth, the Mets handed the final three outs to Sean Manaea. He struggled immensely, recording just one out while allowing three hits and a run. The outing forced Devin Williams into the game. That leaves the Mets short-handed for today’s series finale.…