Lett was a minor league manager in the Reds' chain from 1977 to 1985. He was the Reds' Bench Coach from 1986 to 1989 and again in 1996. He managed in the minors again in 1990, winning the lone South Atlantic League championship for the Charleston Wheelers, coached for the Nashville Sounds in 1991–92, and spent 1993–95 as the Reds' minor-league field coordinator.
