"People say it wasn't Arsenal's strongest side. They were missing their two full backs and Emmanuel Adebayor," said Ferguson.
"But beyond that it's difficult to say how much difference there is between (Mathieu) Flamini and Gilberto (Silva), whose experience has been a vital part of Arsenal's team these past few years. It's difficult to say if they were weak or not.
"Where the match was decided for us in our favour is that we were really positive and that worked for us.
"Some people like Alan Shearer said the way Arsenal played showed the FA Cup doesn't matter to them. But if you listened to what Arsene Wenger said before the game, it didn't come across that way, did it?"