The motive may have been competition for the first-string job, police said Wednesday.
Mitch Cozad was accused of attacking punter Rafael Mendoza in a parking lot Monday night, Evans police Lt. Gary Kessler said.
Mendoza was treated and released from the North Colorado Medical Center Monday night. Coach Scott Downing said Mendoza will not punt in Saturday's game at Texas State University.
"I guess the only identified motive at this point in time is the competition for that position," Kessler said Wednesday.
The stabbing took place in Evans, a small town adjacent to Greeley and about 50 miles north of Denver.
The Greeley Tribune first reported the story in Wednesday's editions.
Cozad was suspended from school and from the team, university officials said in a news release. They did not immediately return calls from The Associated Press but scheduled a news conference later Wednesday.
Kessler said Cozad, a sophomore, was arrested Tuesday on a charge of second-degree assault. He remained in jail as of Wednesday morning, and it was not immediately known whether he had an attorney.
Kessler said Mendoza was attacked from behind and stabbed in his right thigh after parking his car outside his Evans apartment Monday night.
The assailant fled in a black Dodge Charger, Kessler said. About 10 minutes after the attack, a liquor store clerk told police that two men in a car matching that description stopped outside the store, stripped tape off the license plate and drove away.
The clerk gave police the license number and the car was traced to Cozad, Kessler said.
Mendoza, a junior, has averaged 37.6 yards per punt on nine punts in the two games this season.
Downing told the Greeley Tribune he had not spoken to Rafael's doctor and did not know how long he would be out.