DeCastro was in attendance at minicamp this month, but did not participate in drills or talk to the media about the reason he stayed off the field. It appears his ankle might have been the reason why he was on the sidelines.
Mike Garafolo of NFL Media reports that DeCastro has been having his ankle looked at by doctors recently. He had surgery on his ankle during the 2020 offseason and it has reportedly been bothering him for some time.
The results of those consultations with doctors may determine whether DeCastro continues playing. Garafolo reports that he is evaluating his future in the NFL at the moment, so he may not be landing elsewhere as the Steelers move forward without four of their starting offensive linemen from last season.