After taking the loss earlier in the day against the Braves, Gregg said he believed Epstein sent a message through manager Dale Sveum when Sveum placed Pedro Strop in the closer's role for the rest of the season.
"The game didn't unfold the way I wanted it to, but from what they told me over the past few days it makes it difficult to play anyways, let alone knowing what they think," Gregg said. "... For an organization to come out and say, 'Hey, we are going to go a different direction,' a little professional courtesy would have been nice."
Sveum told reporters Wednesday that he was considering using Strop as the closer. Gregg said Sveum informed him of the decision but thought the manager was just the messenger for Epstein.
Epstein arranged a meeting with the media to express his side of the story after Gregg's postgame comments.
"Dale went to Kevin and told him he had done a great job," Epstein said. "He told him we know what he can do and that he had established himself and re-established his career. He said it would really help the organization to take a look at Strop working the ninth inning, maybe once or twice. That is what organizations do when they are looking forward. Kevin has established himself. Strop is the kind of guy you want to see how he responds to the ninth inning."
Epstein said he met with Gregg after the pitcher's media session and told Gregg how disappointed he was with his tirade to the media.
"I called him up to Dale's office to tell him how disappointed I was with him, given the way we treated him this year," Epstein said. "I think it took him a couple of minutes to understand he had misunderstood Dale. He ultimately apologized to me and to Dale. I told him I would sleep on it and decide if we would have any disciplinary action."
After Epstein spoke, Gregg made the trek up to the Wrigley Field press box to reiterate an apology he gave minutes earlier to Sveum and Epstein.
"In a conversation I had with Dale, unfortunately I didn't understand what he was saying," Gregg said. "It kind of got under my skin."
Gregg, who has 32 saves, said he thought he was being permanently replaced by Strop.
"Now that I sat down with Dale and Theo again, I clarified things," he said. "It helped to talk to them and see what they're actually thinking."
Gregg, who signed to be the closer in early April after incumbent Carlos Marmol failed to get the job done, originally said he believes he has no future with the Cubs. Gregg can become a free agent in November. At one point, he had hopes of re-signing with Chicago after the season.
"I think [the change at closer] shows me that they are not that interested in me coming back here," Gregg said after the game. "I will worry about next year next year, but this gives me a good indication of their thoughts going forward."
Epstein said he would consider releasing the veteran pitcher.
This was the third confrontation between the Cubs and staff in the past four days.
Pitcher Edwin Jackson had words with Sveum in the dugout after getting pulled from his start on Tuesday after four innings, and starter Jeff Samardzija had an angry exchange with third-base coach David Bell on Wednesday after the pitcher disagreed with a defensive alignment Bell had put in motion.
"I think it is natural when you have a tough season, a losing season that at the end of the year there will be some brushfires that come up," Epstein said. "Dale went to the player; it is not like he learned of it through the media. There was miscommunication where Kevin misunderstood. He ran to the media, and I told him as a man that I did not respect that."
Epstein said he will make a final decision on Gregg's fate Saturday.
"Theo is a smart man," Gregg said in the press box. "He's not going to have a knee-jerk reaction to something. Unfortunately, I did."