In the trade, the Red Sox dealt top pitching prospect Anderson Espinoza.
"I think that it's important to understand that for a very, very long time, there has been a rule in baseball that if something happens in terms of lack of complete information or disclosure with respect to the trade that the remedy is to rescind the trade," said Manfred. "We offered the Red Sox, early on, the opportunity to seek recession of the trade, and for good baseball reasons, the biggest one being that we were past the Trade Deadline, they elected not to seek recession."
Pomeranz was traded to the Red Sox just after pitching in the All-Star Game for the Padres. In 13 starts with Boston, Pomeranz went 3-5 with a 4.68 ERA. He was scratched from his last start due to soreness in his left forearm. Pomeranz pitched a career-high 169 1/3 innings this season.
If the Red Sox put Pomeranz on the American League Division Series roster, it will be as a reliever.
Pomeranz worked 1 1/3 scoreless, hitless innings as a reliever in Sunday's 2-1 loss to Toronto, striking out a pair of batters.
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.