Idaho had finished last in the Big Sky Conference in the previous
five seasons. Kellerman became a starter as a true freshman, teaming with senior and eventual Big Sky MVP
Don Newman to lead the Vandals to a second-place finish in the regular season (9–5) in
1980 and their first appearance in the four-team
conference tournament. He averaged 11.3 points and 3.4 assists on the season as Idaho finished with an overall record of 17–10. For the
1981 season, Kellerman was joined by
junior college transfer
Ken Owens and led Idaho to eleven consecutive wins to start the campaign. They were 23–3 in the regular season, winning the Big Sky season (12–2) and
tournament titles. In the
NCAA tournament, the Vandals' first appearance, they were seeded seventh in the
West region, but narrowly lost to
Pittsburgh by a point in overtime and finished at 25–4 overall. In
1982, Kellerman and Owens led the Vandals to their best season in program history. Idaho won their first sixteen contests before dropping a pair of January road games to
Montana and
Notre Dame. These were the only losses for the rest of the regular season as Idaho again hosted and won the
conference tournament to enter the
NCAA tournament at 26–2 and ranked eighth in
both major polls. Third-seeded in the
West region, the Vandals won their second round contest over
Iowa 69–67 in overtime and advanced to the Sweet 16, but fell to
Oregon State to finish at 27–3 overall. Kellerman was again honored as a first-team All-Big Sky pick, but lost the conference player of the year award to his backcourt partner Owens, the third Vandal honored in as many years. With the loss of Owens and starting forward
Gordie Herbert to graduation, the
1983 team took a step back in the conference, tying for third place (9–5). Idaho became the first Big Sky team to appear in the
National Invitation Tournament (NIT), but lost at Oregon State and finished at 20–9 overall, As a senior, Kellerman posted a career-high 17.9 points per game and was named All-Big Sky for the third consecutive season, ending his collegiate career as Idaho's all-time leading scorer (since eclipsed) with 1,586 points. In his four seasons as a starter, the Vandals' overall record was , with three national postseason appearances. In 1988, Kellerman was named to the Big Sky Conference's 25th anniversary team, along with teammate Owens. In 2006, he was inducted into the Northern Idaho Athletic Hall of Fame and two years later was named to the University of Idaho Athletics Hall of Fame. ==Professional career and later life==