A first-round selection in the 1987 MLB draft, he played for the Texas Rangers, Seattle Mariners, Boston Red Sox and Detroit Tigers.

[7] In 1988, he was promoted to the Port Charlotte Rangers of the Class A-Advanced Florida State League, where he hit .245 in 122 games.

[1] Haselman spent most of 1993 as the Mariners back-up catcher and hit his first home run on May 8 off of Jim Deshaies of the Minnesota Twins.

On June 6, 1993, Haselman was hit by a pitch thrown by Baltimore Orioles pitcher Mike Mussina, leading to him charging the mound and igniting a bench-clearing brawl.

Haselman shattered his bat, sending a Woody Williams' offering sailing over the Green Monster to give the Red Sox their first walk-off win of their 1995 American League East division-winning campaign.

Haselman's only postseason appearance was during the 1995 American League Division Series, when he played in one game against Cleveland and was hitless in two at bats.

[11] The Red Sox traded Haselman (along with Mark Brandenburg and Aaron Sele) on November 6, 1997, to the Texas Rangers for Damon Buford and Jim Leyritz.

[1] The Tigers traded Haselman back to the Rangers (along with Frank Catalanotto, Francisco Cordero, Gabe Kapler, Justin Thompson and a minor leaguer) on November 2, 1999, in exchange for Juan González, Danny Patterson and Gregg Zaun.

[1] Haselman rejoined the Tigers again on a free agent contract on January 20, 2003, but was released on March 27, before the season started.

[7] Haselman signed as a minor-league free agent with the Baltimore Orioles on December 3, 2003, but retired at the age of 37 before playing in any games.

[2] Boston then offered him a manager position in the minor leagues, but Haselman declined, as he did not want to spend that much time away from his family.

[15][16] In 2010, Haselman returned to professional baseball as manager of the Class A Bakersfield Blaze, a California League affiliate of the Texas Rangers.

[2] Haselman joined the Los Angeles Dodgers organization in 2014 as the manager for the Great Lakes Loons of the Midwest League.

[22][23] Haselman joined the Angels' major-league staff in January 2022 as the team's catching instructor, succeeding José Molina.