He grew three inches (7.5 cm) between committing to the Vandals and arriving on campus, making him a taller guard, especially in the mid-major Big Sky Conference.
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.
For the 1981 season, Kellerman was joined by junior college transfer Ken Owens and led Idaho to eleven consecutive wins to start the campaign.
[2] Kellerman received individual recognition after averaging 16 points and 3.2 assists a game and earning Big Sky Player of the Year honors as a sophomore.
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.