At the time of his death, Klein was the executive director of the Atlantic League of Professional Baseball, an independent circuit operating in the Northeast United States.

[1] After retiring from the field, he spent 16 years as a minor league manager and front office executive with the franchise, beginning in 1969 when it was still the expansion edition of the Senators, and continuing after it became the Texas Rangers in 1972.

The Indians were seen as a dark-horse contender for the AL East title in 1987 (making the cover of the spring training edition of Sports Illustrated), but instead they collapsed completely, losing 101 games and falling into the division basement.

In 1992, he moved on to the Detroit Tigers, who were in a period of transition with former University of Michigan football head coach Bo Schembechler serving as the team president.

Klein was associated with the Atlantic League from its founding until his death on August 23, 2017, at Temple University Hospital in Philadelphia from complications from quadruple bypass surgery, only one day after his 75th birthday.