The youngster made 52 appearances under the Portuguese last season but only half of those were starts.
Goals in internationals against Spain and Switzerland this month have led to many questioning whether Rashford, now 20, should look for a move elsewhere.
And Ferdinand has added fuel to the fire by suggesting Mourinho did not have the same level of trust in Rashford as he does with other players.
“I look at it from Rashford’s point of view,” he said.
“If I am sitting there as Marcus Rashford and someone says to me, ‘Do you think your manager believes in you as his main, best striker and that he will build his team around you?’ I would say, ‘No. Because I am not starting every game.’
“You ask any player. Coming on as a sub — that means nothing. You can bring me all the minutes in the world, I don’t care. I don’t want to come on for 10 minutes every game. I want to walk out on that pitch as the starter.
Romelu Lukaku plays ahead of Rashford because, firstly, he is a better goalscorer and, additionally, has more experience in the Premier League. The two come hand in hand.
But this does not imply that Mourinho does not trust Rashford. Not in the slightest. There was a time when Lukaku was in the same position as Rashford: in fact, aged 20, the latter has achieved much more.
Put simply: Rashford is at an earlier stage of his development. It would be coarse to equate this with a lack of trust on Mourinho’s part. As the boss said last week, he is no Dominic Solanke.