NEW YORK -- Nestor Cortes was slated to start Wednesday against the Baltimore Orioles as the New York Yankees look to clinch the AL East title with a win. Instead, the left-hander was placed on the 15-day injured list with a left elbow flexor strain. 

It's an alarming development 10 days before the Yankees are scheduled to begin postseason play.

Marcus Stroman, who recently shifted to the bullpen, will start in Cortes' place Wednesday. Stroman last pitched eight days ago, throwing three innings in his first and only relief appearance this season.

The Yankees also recalled Cody Poteet from Triple-A. Poteet was recently activated from the 60-day injured list and sent to Triple-A.

Cortes' recent performance did not suggest he's been dealing with any elbow trouble. Beginning with a brief demotion to reliever, Cortes has given up one run with 18 strikeouts in 15⅓ innings over his past three outings.

The stretch began with Cortes tossing 4⅓ hitless innings in his first relief appearance of the season against the Chicago Cubs -- and afterward sharing his frustration with moving to the bullpen. He returned to the rotation five days later, limiting the Boston Red Sox to one run with nine strikeouts across five innings. On Sept. 18, he held the Seattle Mariners to four hits over six scoreless innings.

Cortes, 29, has a 3.77 ERA across a team-leading 174⅓ innings pitched. He has made 30 starts but is expected to return to the bullpen for the playoffs.

The Yankees have, for the most part, benefited from good injury luck in recent weeks. Clarke Schmidt, Anthony Rizzo, Jon Berti, Ian Hamilton and Luis Gil also have been reinstated from the injured list since Sept. 1. The reinforcements made the Yankees more whole than just about any other club in baseball.

It also gave the Yankees a problem teams would love to have down the stretch: Six healthy capable starting pitchers for five spots. The surplus prompted the Yankees to move Cortes to the bullpen for one rotation turn before switching Stroman with him for the past two turns.

Now that surplus has taken a hit.