The smile wasn’t masking any gloom festering during the pitcher’s three-week-old offseason. If anything, the Wiffle Ball blasts for charity were cathartic for Buchholz, who hadn’t watched a pitch of his sail out since the Game 3 loss to the Angels in the American League Division Series.

Buchholz hasn’t watched tapes of his five-plus-inning performance, but he spent plenty of time replaying the outing in his head.

“You always go back mentally and try to pick out the things you think you did well or think you need to work on,’’ Buchholz said. “And there was definitely both of those things throughout that outing.’’

Buchholz was joined by David Ortiz, former Sox players Kelly Shoppach and David Murphy, and the Astros’ Hunter Pence and the Padres’ Heath Bell, who were at Reebok headquarters to promote the company’s line of new products and participate in a home run derby for charity.

Buchholz has a busy offseason lined up - he’s getting married to “Deal or No Deal’’ model Lindsay Clubine in two weeks - but he said he’s not concerned about getting ready for spring training.

He said he hopes to improve the cerebral aspects of his game.

“There’s definitely still some ups and downs that I went through this year, but just not to the extreme that there were last year,’’ he said of his mental stumbling blocks.

One of his goals is to be less distracted by base runners, which was an issue in his first postseason start. Handed a 5-2 lead to start the sixth inning, he allowed three straight runners and got pulled.

“I’ve always been told I have a good move to first base, and sometimes it’s in my head that when someone gets on first, I want to pick them off just so I don’t have to worry about them,’’ he said. “Sometimes I don’t even think about it and I throw over there, and that’s something that I’ve gotten better at but there’s still a lot of room for improvement.’’

Late-season pickup Victor Martinez may be the one to help Buchholz build on his confidence.

“It takes time for pitchers and catchers to be able to work together and be able to be efficient together,’’ said Buchholz. “Vic came in, in the middle of a grind, and helped the team win.

“I think I threw to him more than anybody did, so we were able to sit down and talk about all the stuff that we could work on and make better and some of the things to refine and perfect. It’s a process, but it worked for us this year and I can’t wait to get back to it next year.’’

Ortiz, who drew the greatest cheers from the crowd yesterday, said he’s enjoyed watching former teammate Pedro Martinez return to the mound in the World Series.

“Actually, Pedey, he is throwing the ball really good, man. He doesn’t have the same speed that he has before but he’s a good pitcher.’’

Ortiz did offer general manager Theo Epstein some advice.

“All I know is Jason Bay is a free agent, and they better sign him,’’ Ortiz said. “He’s a great player.’’

But even if the left fielder were to leave, Buchholz isn’t concerned.

“We’d have to fill his spot for sure and that’s going to be tough to do, but the Red Sox have plenty ways of working it. They usually figure it out,’’ he said.