Mourinho left Anthony Martial on the bench until the final 10 minutes of Saturday's Manchester derby.
"Already he seems out of sorts," Cascarino wrote in his column for The Times.
"He is out of the team and could be the latest wide man to fall victim to Jose Mourinho's management.
"The defeat by City exemplified Mourinho's issue with wingers.
"He wants them to be runners, thinking as much, if not more, about tracking their full back as they do about attacking.
"If they have a decent crossing ability then that helps."