Mackey spent 60 days at a rehab center run by John Lucas, and then went on to a successful career in minor league basketball. In 1991, he was a mid-season replacement coach for the Miami Tropics of the United States Basketball League and led the team to the title game. In 1996, he coached the Portland (Maine) Mountain Cats to the Final Four of the USBL. Following his stint with the Mountain Cats, Mackey captured three consecutive USBL Championships, with the Atlantic City Seagulls, something no other coach in the USBL has done.