He walks by Dustin Pedroia, who whispers something to send Byrd into hysterical laughter. Darnell McDonald comes over and the two give each other a handshake and a hug. The clubhouse attendants stop to chat while Jarrod Saltalamacchia says hello.
Finally, Byrd inches closer to his locker. He's just a few feet away when he stops, crouches down, and starts throwing punches. He's jabbing right, ducking down, popping up and throwing a left haymaker. Had anyone been on the other side of this, surely they would be in pain.
But Byrd doesn't feel any. Not after being hit in the face by a 93-mph fastball a year ago at this very ballpark, and not after getting called out by those who believe the 34-year-old outfielder is on the decline because 43 at-bats with the Cubs this season left him with a .070 batting average and .219 OPS.
"This guy is awesome," says Pedroia.
The chirpy second baseman is often known for keeping the mood light. But when he's asked if Byrd needs to prove himself with a new team after the Cubs traded away the former All-Star for Michael Bowden, a 25-year-old pitcher with a 5.46 ERA and 1.58 WHIP in 62 2/3 Major League innings, Pedroia gets serious. He shakes his head from side to side.
"No, man," Pedroia says. "He's proven himself for a long time. Everyone on this team knows what he brings to our club."
All year, Byrd has been on a mission. He arrives at the park hours earlier than he used to. Ever since a 2007 conversation with Kenny Lofton, who was 40 at the time, Byrd has learned that with every year of age, a ballplayer must work harder and harder.
And of course, age is also a popular blame for poor play, as some claim Byrd's poor start to 2012 -- paired with a down year in 2011 -- is because the 34-year-old is simply "on the decline."
"People are going to have their opinions, and I can appreciate that," says Byrd, who cooled down from his boxing session and now stands calmly in front of his locker. "But when I go out there, a lot of people don't even know how old I am, because I don't look like it.
"Everyone talks about me having a down year last year. I hit .276 with nine homers. But they forget I was hit in the face with a 93-mph fastball and came back. And then you look at this year and people talk about my numbers being down, but no one says, 'Where is he going to be in September?' Or, 'Look at his track record.'
"Older guys have a track record for a reason. Because we've been around for so long, we know how to do it and we know how to grind through. And I know what it'll be like at the end of the season."
Since joining the Red Sox and replacing Jacoby Ellsbury, the American League MVP runner-up last year who injured his shoulder in April, in center field, Byrd has been solid, but not overwhelmingly noticeable. While he's played strong defense in center field, converting all 23 putout opportunities with good speed to cover the deepest parts of Fenway Park, his batting average stands at a mild .256 through 46 at-bats with Boston.
It may appear to be consistent with his declining average over the last three seasons. But if you dig deeper, it's really not too far off his career norm.
Byrd has been well known as one of those hitters who heats up with the weather. "I'm a Southern boy," says the Florida native, and his statistics prove it. While he's averaged .261 and .263 in the months of April and May throughout his 11-year career, that mark jumps to .298 in June and .287 in July, when his OPS (.796) is more than 100 points higher than his OPS in April (.691).
"I never hit when it's cold," he says. "But I'm not worried about that right now. I'm getting my hits, getting my feet wet over here, and the homers will come."
The homers should come; "I'm a 10- to 15-home-run guy," he says. And while Byrd has just one extra-base hit on the season, Red Sox manager Bobby Valentine, who has known the outfielder since he was first coming through the Phillies organization, is sure that the power is coming.
"I think his swing is still developing to where he's feeling good about it," said Valentine. "And I think there's a power factor there that we're going to see also."
Byrd just needs a chance, and he's hoping the Red Sox continue to provide him with one.
Because while a hitter's prime is often defined from age 27 through age 31, Byrd is three years past that. But he's more experienced. He's smarter. He's working harder. And if history is any indicator, he'll prove that the trade general manager Ben Cherington made to acquire him was worth it.
"You have to trust the track record," said Orioles' manager Buck Showalter. "If they're working hard and physically in good shape, managers like having those guys, because sooner or later, they always revert to their track record."
Jason Mastrodonato is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.