Drew Pomeranz

Boston Red Sox's Drew Pomeranz pitches during the first inning against the New York Yankees in Boston, Sunday, Sept. 18, 2016. (AP Photo/Michael Dwyer)

(Michael Dwyer)

NEW YORK -- Red Sox lefty starter Drew Pomeranz is experiencing forearm discomfort and has been scratched from his start Thursday at Yankee Stadium. Henry Owens will start instead.

"He's come out of his last start a little bit more sore," Red Sox manager John Farrell said. "There's been additional need for recovery time. The total number of innings pitched. There's been a combination of factors. So he's not shut down but he's not starting Thursday. We need to get him back out on the mound hopefully by the end of the week to determine a bullpen role going forward."

If Pomeranz makes the playoff roster, it will be as a reliever. He is done starting this season.

"So that settles our rotation going forward," Farrell said.

Rick Porcello, David Price, Clay Buchholz and Eduardo Rodriguez will start for Boston in the postseason, not necessarily in that order.

"The forearm area is where he's experiencing some of the discomfort," Farrell said. "Needs a few extra days. So combined with his career high in innings pitched -- I think he's roughly at 170 innings -- we're backing him out of his last start."

Is this related to the San Diego situation?

The Red Sox acquired Pomeranz from the San Diego Padres on July 14 for top pitching prospect Anderson Espinoza.

Major League Baseball suspended Padres GM A.J. Preller on Sept. 15 because it found out Preller instructed the Padres medical staff to create two separate medical files for players, one available to the league and one available for only the team, according to an ESPN.com report. It was a practice meant to hide any medical information from future trade partners.

The Padres hid information about Pomeranz.

"That I can't really comment on," Farrell said when asked if this discomfort/soreness is related. "I do know what the player needs is some additional time. So what is attached to that previously, I don't have all the specifics. But he's not going to pitch Thursday."