"I learned Saturday evening that the four had violated team rules prior to the Texas A&M game," he said.
Patton wouldn't elaborate on the nature of the violations.
The Aggies dominated the Buffs in Boulder Saturday, winning 92-77.
Missing the four players will likely hurt the Buffs on the offensive end of the floor. Combined, the four average over 32 points per game. Ashby is the team's leading rebounder (6.1), while Hall leads the team in assists (4.4).
Both Copeland and Hall have played in all 24 games this season for the Buffaloes, who enter Tuesday's game with a 13-11 overall record, including a 4-8 mark in league play.