The England international moved to Old Trafford from Aston Villa last year but a lack of game-time due to a host of injuries have hampered the 27-year-old's campaign.
"Ashley Young is in danger of becoming a one-trick pony," Cascarino wrote in The Times. "He is a full international, signed for a lot of money. He needs to a do a lot more than cut inside and lay the ball off."
Young has featured in five games for the former Premier League champions this season after returning from injury.