College career

Thomson was a standout for the Stratford Nationals of the Intercounty Baseball League.^[3] From there, he was recruited to St. Clair County Community College where he played baseball for one year.^[3] After a year, he transferred to the University of Kansas.^[3][2] Thomson led the Jayhawks in hits in 1984 and 1985 and holds the school record for the highest single-season batting average.^[2]

Detroit Tigers

Thomson was selected by the Detroit Tigers in the 32nd round of the 1985 Major League Baseball draft from the University of Kansas. He played catcher and third base in the Tigers' minor league system until 1988, reaching as high as Class A.^[1] In 661 at bats, he hit .225/.312/.304 with seven home runs and three steals.^[1] He played 136 games at catcher, 55 games at third base, and pitched in one game.^[1]

International career

Thomson represented Canada in baseball, which was a demonstration sport, in the 1984 Summer Olympics in Los Angeles.

Detroit Tigers (1988–1989)

From 1988 to 1990, Thomson served as a minor league coach in the Detroit Tigers organization.^[3] Thomson says he got into coaching because "I wasn’t a good enough player. The game sort of forced me into coaching. I was lucky enough the Tigers thought enough of me as an evaluator, teacher and an organizer to offer me a coaching position."^[2]

New York Yankees (1990–2017)

In 1990, Thomson joined the New York Yankees organization as a third base coach for the team's Class-A affiliate in Fort Lauderdale. He moved into the front office in 1998 as a Field Coordinator, and became Director of Player Development in 2000. Prior to the 2003 season, he was named Vice President of Minor League Development, and was named to the Yankees major league coaching staff in November of the same year. Thomson ran the Yankees’ spring training camp.^[4] Yankees manager Joe Torre nicknamed Thomson "Topper" because Thomson was always on top of everything while running the spring training camp.^[4]

During the 1994–95 offseason, he managed the Canberra Bushrangers of the original Australian Baseball League.^[5]

On September 27, 2006, Thomson took over as first base coach of the Yankees in place of Tony Peña, who had learned before the game his father had died, then filled in at the position for four games before Peña returned in time for the season finale on October 1.

Prior to the 2008 season, incoming manager Joe Girardi named Thomson his bench coach.^[6] On April 4, 2008, Girardi became ill due to a respiratory infection and designated Thomson to manage that night's game against the Tampa Bay Rays.^[7][8] It was Thomson's first major league game as a manager, at which he became the first Canadian to manage a Major League game since George Gibson for the Pittsburgh Pirates in 1934; the Yankees lost 13–4.^[9][7] Thomson also managed the April 5 game due to Girardi's illness, where the Yankees once again fell to the Rays by a score of 6-3^{[10] [11]}

He served as the team's third base coach for six seasons and was a member of the coaching staff for the Yankees' 2009 World Series championship. Prior to the 2015 season, Thomson was named bench coach, which was a role he held until 2017.^[12]

Philadelphia Phillies (2018–present)

Thomson with the Phillies in 2019

Thomson held the position of Philadelphia Phillies bench coach from 2018 to 2022.^[13] He initially got the assignment under first year manager Gabe Kapler.^[14] Kapler was fired after two seasons, but Thomson remained the Phillies’ bench coach under new manager Joe Girardi, who had worked with Thomson while with the Yankees.^[14] Prior to the 2022 season, Thomson had stated to the team that it would be his last as a bench coach, intending to retire after the completion of the season.^[15]

On June 3, 2022, the Phillies fired manager Joe Girardi after a disappointing 22–29 start to the season.^[14] The same day, Thomson was named the Phillies’ interim manager.^[14] Thomson became the first Canadian full-time manager since George Gibson managed the Pittsburgh Pirates in 1934.^[16] The Phillies won their first game under Thomson, blanking the Los Angeles Angels 10–0.

On July 13, 2022, Thomson managed a game against the Toronto Blue Jays, at the Rogers Centre, to become the first Canadian to manage a major league game in Canada.^[16]

The Phillies secured a 3–0 win over the Houston Astros to clinch their first playoff berth since 2011 on October 3, 2022.^[17] After the game, Thomson said in the locker room "We’re not done. After Wednesday, we have 13 more wins and [then] we’re world champions."^[17] With the Phillies making the playoffs, Thomson became just the fourth interim manager in MLB history to take over a team at least 7 games under .500 and lead them to the postseason.^[17] In the Wild Card Series, against the St. Louis Cardinals, the Phillies swept the Cardinals 2-0 for their first playoff series win since 2010.^[18] In the National League Division Series, the Phillies faced off against the defending World Series champion Atlanta Braves.^[19] The Phillies defeated the Braves, 3-1, and reached the National League Championship Series for the first time since 2010.^[19]

On October 10, 2022, the Phillies removed the interim tag from Thomson's title and formally named him the 55th manager in franchise history, with a two-year contract.^[20] He then led the team to win the 2022 National League Pennant. After clinching a trip to the 2022 World Series, Thomson reiterated that there was more work to be done telling his team that they had "beaten three really good teams, and there was one to go."^[21] The Phillies lost to the Houston Astros in six games. The Astros, who were down two games to one, won three games in a row to the secure the World Series. In Game 6, Thomson received scrutiny from some in the media for his decision to take out starter Zach Wheeler after 70 pitches. Wheeler was replaced by José Alvarado, who gave up a home run to Yordan Alvarez, which gave the Astros the go-ahead lead in the sixth inning.^[22]