The phrasing is all so clinical, precise verbiage that all means the same thing: A ballplayer on the move. Steve Pearce experienced all of these designations in 2012 alone: released, signed as a free agent, purchased, selected off waivers. He bounced from the Minnesota Twins to the Yankees to the Baltimore Orioles to the Houston Astros, then back to the Yankees and the Orioles again. His Yankees career lasted just 12 games, and he hit .160.

“It went by fast, but I do have memories,” Pearce said late Thursday at Fenway Park, after his best day in the major leagues. “What I remember most are the guys in the clubhouse. It was a very, very stacked team when I played there. I was just looking around, I was like: ‘Hall of Famer, Hall of Famer, Hall of Famer. Where do I even fit in on this team?’”

Pearce fits in snugly now with the Boston Red Sox, as a platoon first baseman who devours left-handed pitching — and some right-handers, too. He launched three homers and drove in six runs in Thursday’s 15-7 victory over the Yankees, his first three-homer game at any level.

“I’m proud of him,” said Alex Cora, the Red Sox manager. “His role, it’s not easy. But he understands where he’s at, why we brought him here.”

The Red Sox rise over the .500 mark like the John Hancock Tower, stacking win after win after win in the Back Bay. They improved to 76-34 on Thursday, and have long had the luxury of precision roster construction, as shown by Pearce’s presence in the cleanup spot.

He was also in that slot for his first game with Boston, on June 29 in the Bronx, also against C. C. Sabathia. Pearce homered off Sabathia in the third inning Thursday, then connected off Jonathan Holder in the fourth and Luis Cessa in the sixth.

The shot off Cessa, which struck a light tower over the Green Monster, made him the 14th Red Sox player to hit three homers in a game at Fenway. The list includes three Hall of Famers — Ted Williams, Bobby Doerr and Jim Rice — but not Carl Yastrzemski, Manny Ramirez or David Ortiz. Only Mo Vaughn and Kevin Millar had done it against the Yankees.

Pearce walked in the eighth inning with a chance for his fourth home run, a feat accomplished just 18 times in major league history, most recently by J.D. Martinez, who was on deck as Pearce faced Cessa. He drew a walk on five pitches, and did not take a swing.

Pearce had already hit a solo homer, a two-run homer and a three-run homer. If he’d had a chance for a grand slam, he said, smiling, “Maybe I would have expanded the zone that last at-bat.”

The game was an extreme example of exactly why Dave Dombrowski, Boston’s president of baseball operations, acquired Pearce from Toronto for a prospect more than a month before the nonwaiver trade deadline. The Red Sox had released another right-handed-hitting first baseman with power, Hanley Ramirez, making the left-handed Mitch Moreland the everyday first baseman.

Pearce filled a role as a right-handed complement with stellar numbers against Sabathia (now .316 with three homers) and other lefties like J.A. Happ, who is now with the Yankees. Pearce has five career homers off Happ, with a .357 average.

“We decided to go with Mitch at first base, and felt like we were one bat on the bench away from being really, really good offensively,” Cora said. “We play him against lefties and somebody takes a day off, which benefits them, and he has quality at-bats against righties. We knew he was going to perform.”

Pearce is hitting .358 for the Red Sox (19 for 53) in his limited role. He has now played for every team in the American League East, joining the former infielder Kelly Johnson as the only players to do so. He has carved a niche in a game that regularly turned him away a few years ago.

“The word ‘quit,’ that wasn’t an option,” Pearce said. “I knew I could play at this level. I just needed an opportunity. I waited a long time for that opportunity, and took advantage of it.”

The Red Sox bashed 19 hits in all on Thursday, including three from Ian Kinsler, the second baseman whom Dombrowski acquired in a trade with the Angels on Monday.

Dombrowski had been on the field just before the game, helping his 88-year-old mentor, Roland Hemond, toss the ceremonial first pitch.

Hemond, a Rhode Island native, brought Dombrowski into baseball with the Chicago White Sox in the 1970s. He must have been proud of his protégé on Thursday, when a trade piece delivered exactly as planned.