Ferguson pinpointed Scholes' influence as a substitute in their comeback to win 3-2 at Southampton last time out as an example.
He said: "Paul once again came on in the last game against Southampton and it was like opening a door to another room.
"He just brought order to the game, his selection of passes, the accuracy of his passing, changed the whole game for us.
"Robin van Persie quite rightly said he thought Scholes was Man of the Match even though he was only on for 25 minutes, he was phenomenal.
"Southampton didn't know what to do with him, which is great credit to the lad."