In 1989 he won gold at the Pan American Championships and was runner-up at the Olympic Festival; he won the U.S. national freestyle championship in 1990 and 1991; took first in the 1993 World Cup, while placing second in 1992 and third in 1990; placed fifth at the 1990 World Championships; won the 1992 World Cup Grand Prix; and was the alternate for the USA at the 1992 Olympic Games.

[1][2] Koll joined Cornell University as an assistant wrestling coach in 1989.

In late August 2023, Koll accepted the head coaching position at his alma mater, the University of North Carolina at Chapel Hill.

His father, Bill Koll, was a legendary three-time NCAA wrestling champion for Iowa State Teachers College (now the University of Northern Iowa) and a fifth-place finisher at the 1948 London Olympics.

[4][5] Bill later became the head coach at Penn State University, and from 1965-1978 he led the team to a 127-22-7 record.