The New York Yankees have to deal with another serious injury.

On Tuesday, manager Aaron Boone announced that the Yankees have placed third baseman Jazz Chisholm Jr. on the injured list because he suffered an injury to the ulnar collateral ligament in his left elbow. The team does not yet know the exact severity or whether he will need surgery.

New York has struggled with serious injuries all season, most notably lengthy IL stints for Gerrit Cole, Anthony Rizzo and Clarke Schmidt. Chisholm was the team’s big trade-deadline addition and hit the ground running in the Bronx, so this is a major blow.

In his 14 games as a member of the Yankees, Chisholm had a .316 batting average, a .361 on-base percentage and a .702 slugging average. He has seven home runs, 11 RBIs, an OPS of 1.062 and a WAR of 0.9. In 101 games with the Miami Marlins prior to that, he had only posted 1.2 WAR, so the move to New York seemed like a good fit for him.

Chisholm was injured in Monday night’s 12-2 loss to the Chicago White Sox. He sustained the injury when he slid into home plate in the fifth inning, touching home plate before White Sox catcher Korey Lee could tag him. Chisolm shook out his left arm in the dugout during the game and eventually left the game in the seventh inning.

The loss of Chisolm is a major blow to the Yankees as MLB enters the home stretch. New York enters Tuesday’s games for first place in the American League East a half-game behind the Baltimore Orioles. Chisholm has provided momentum since his arrival, so if he has to miss one day, it could be damaging.