He spent all or parts of three seasons in Major League Baseball (MLB) on the coaching staff of the Detroit Tigers and Boston Red Sox.
After attending Lorain County Community College, he signed with Detroit in 1974 and pitched for nine seasons in the Tiger farm system, including service with the Triple-A Evansville Triplets during 1978–1980.
[2] He also pitched for the Leones del Caracas champion team of the Venezuelan Winter League during the 1979–80 season, and made a start in the 1980 Caribbean Series.
From September 2001 through spring training of 2002, he was the major-league pitching coach of the Red Sox, but he was reassigned in favor of Tony Cloninger when Grady Little replaced Joe Kerrigan as manager on the eve of the 2002 season.
During 2003–2005, Treuel served as manager of the rookie-level Gulf Coast Red Sox, then began his second term as Boston's roving minor-league pitching coordinator in 2006.