Butler has missed the last two practices with the issue and could be a candidate to go on injured reserve for his rookie season, per Rapoport.
However, Cardinals HC Kliff Kingsbury says it’s too early to tell if the injury will keep Butler out for the 2019 season, per Darren Urban. He confirmed Butler will miss the rest of the preseason.
An avulsion fracture is an injury to the bone in a location where a tendon or ligament attaches to the bone. When an avulsion fracture occurs, the tendon or ligament pulls off a piece of the bone.
Butler, 22, was drafted by the Cardinals in the fourth round out of Iowa State. He signed a four-year rookie deal worth $3.3 million.
During his college career at Iowa State, Butler caught 110 passes for 2,149 yards receiving and 18 touchdowns over the course of 34 games and three seasons.