NEW YORK — The New York Mets’ beleaguered pitching staff is taking another hit.The Mets are putting right-handed reliever Austin Warren on the 15-day injured list, according to people familiar with the situation who were not authorized to speak freely on the topic. The specific nature of Warren’s injury is unknown. He was scheduled to undergo tests Wednesday.Warren winding up on the injured list allows the Mets to recall a pitcher they recently optioned, such as right-hander Tobias Myers.Warren was a revelation for the Mets this season until his latest appearances. He gave up five earned runs, four hits and one walk without recording an out in New York’s 16-12 loss against the Kansas City Royals on Tuesday. Three days earlier, in two innings against the Atlanta Braves, Warren gave up four runs. In 35 innings (26 games), he holds a 4.63 ERA.Before those two outings, however, Warren’s ERA was 2.45.Warren’s injury puts the Mets’ bullpen in a further bind before New York even starts selling off pitchers ahead of the Aug. 3 trade deadline. After not making the team out of spring training, Warren emerged as a reliable option in what’s been a relatively strong bullpen. Lefty relievers A.J. Minter and Brooks Raley profile as obvious trade candidates, while others like Luke Weaver could also be on the move.