Despite his big-money move from RB Leipzig this summer, the Slovenian forward has yet to start under Ruben Amorim after two weeks in action.
The limited opportunities under Amorim have left the former England international concerned about his development at Old Trafford.
"Get the ball into him. He isn’t going to be an easy day’s work. Get it into him and make them defend. But we are playing it around him," Ferdinand said on his Youtube platform.
"Sometimes it’s like really basic, fundamental things. Get it into someone who can cause problems but we go against that. So that was my main concern, you are not getting to see who he is.
"I would rather you play it into him and he look rubbish so we know what we’ve got because, right now, I don’t know what he is or what he’s doing. I’m not pointing the finger but you have got to help your team-mates find their feet in the team."