In an interview that appeared in The Boston Globe on Monday, Lester admitted it was "the wrong thing to do."
A Globe article last week cited Lester, Josh Beckett and John Lackey as Red Sox starters who drank alcohol in the clubhouse during games in which they weren't pitching, while also ordering takeout fried chicken and playing video games.
While taking accountability, Lester said that he didn't believe that the "bad habit" he and some of the other starting pitchers engaged in was the reason for an epic free-fall by the Red Sox, who became the first team in Major League history to have a nine-game lead in the standings in September and not make it to the postseason.
"There's a perception out there that we were up there getting hammered and that wasn't the case," Lester told Globe reporter Peter Abraham. "Was it a bad habit? Yes. I should have been on the bench more than I was. But we just played bad baseball as a team in September. We stunk. To be honest, we were doing the same things all season when we had the best record in baseball."
Lester wanted to make it clear that he and other pitchers weren't getting drunk during games.
"It was a ninth-inning rally beer," Lester said. "We probably ordered chicken from Popeye's like once a month. That happened. But that's not the reason we lost. Most of the times, it was one beer, a beer. It was like having a Coke in terms of how it affected you. I know how it looks to people and it probably looks bad. But we weren't up there just drinking and eating and nobody played video games. We watched the game."
Terry Francona, who had a mutual parting of ways with the Red Sox after eight years as manager, said shortly after the season that he didn't believe his players were pulling for each other as much in 2011 as in years past.
Francona also spoke of not being able to "reach players" this season that he had reached in the past.
"I love Tito and he did a great job for us when he was here. On a personal level, I was more than grateful for what he did for me and my family," Lester said.
That said, Lester essentially indicated that his former manager was right when he said the Red Sox need a new voice of leadership.
"There comes a time when your authority is no longer there. You kind of run your course," Lester said. "People knew how Tito was and we pushed the envelope with it. We never had rules, we never had that iron-fist mentality. If you screwed up, he called you on it. That was how it worked.
"I never saw guys purposely breaking rules or doing the wrong thing in front of him and rubbing it in his face. But this particular team probably needed more structure."
Lester felt that one of the starting pitchers needed to say something in light of all the recent reports.
"Consider us a unit when it comes to these accusations," Lester said. "We either fall together or rise above it all together, whether they like it or not. Things got magnified because we lost and sources started telling people what happened, which has me upset because if you're going to say something, be a man to put your name to it. But we're not bad people and we're not a bad group of guys.
"Are there things I regret? Sure there are. But nothing happened that had me unprepared to pitch. I don't blame people for wanting answers because we had a hell of a team and we lost. You can't have a team that gets paid like we get paid and loses and not expect people to want answers."
Lester, who won 15 games in 2011, disputed the suggestion that Red Sox pitchers let themselves get out of shape, though he didn't deny there might have been some weight gains over the course of the season.
"It's probably because of how we eat," Lester said. "We have some crazy hours with the travel and you get in at 4 a.m. and you get room service or something quick. But unless your body fat is going up 10 percent or something like that, you don't have a problem.
"I've heard what people are saying in Boston. I can tell you that guys were in the weight room. Guys were doing their shoulder [exercises] and guys were prepared to pitch. If we win a few more games in September and make the playoffs, none of this comes out. But we didn't and that's on us as a team and on me personally. I take a lot of the blame for this -- a lot.
"In September, a lot of people had their weight jump up and I can see where the owner would look at that and say we're out of shape. But that's not the case. Every time I was in the weight room, there were guys busting their [butts]."
Though Lester pitched fairly well while taking a no-decision on three days' rest in the fateful regular-season finale at Camden Yards -- a 4-3 loss in which the Orioles rallied from behind with two out in the ninth inning -- he said he believes he let the team down by going 1-3 with a 5.40 ERA in September. He was 0-3 with a 10.54 ERA in three starts from Sept. 11-24.
"It bothers me because I'm supposed to be a stopper," Lester said. "I picked a terrible time to stink. That's on me."