Pomeranz will be used as a reliever in the postseason if he is on the roster.
Boston's postseason rotation will include Rick Porcello, David Price, Eduardo Rodriguez and Clay Buchholz if manager John Farrell elects to go with four starters.
"The forearm area is where he's experiencing some of that discomfort. He needs a few extra days," said Farrell. "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. We need to get him on a mound hopefully by the end of the week to determine a bullpen role going forward."
That role wouldn't be unfamiliar to Pomeranz, who has made 58 of his 137 career appearances as a reliever. The issue is whether Pomeranz is healthy enough to keep pitching.
"I think at this point in time we're looking at the needs of Drew," said Farrell.
Padres general manager A.J. Preller was recently suspended 30 days by Major League Baseball for not being completely forthcoming with Pomeranz's medical records before the trade to Boston in July. Farrell wouldn't say if those issues were related to Pomeranz not pitching in New York.
"That I can't really comment on," Farrell said. "I do know that what the player needs is some additional time. What is attached to that previously -- I don't have all the specifics, but he's not going to pitch Thursday."
In 30 starts this season, Pomeranz is 11-12 with a 3.35 ERA. Since coming to Boston in a trade for prospect Anderson Espinoza, he is 3-5 with a 4.68 ERA.
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.