Wayne Rooney scored the only goal of the game.
"It has been a great season for us," said Ferguson.
"Most of the time we have been playing well and obviously today doesn't reflect the 15 points ahead we are, it is the previous six months."
Ferguson refuses to accept a 20th championship is already secure even if it will only take 13 points from nine games to be mathematically certain following Manchester City's defeat at Everton, and United are on course to break their own record for an 18-point title-winning margin.
"People can say what they like," he said.
"You don't get points or medals for being complacent and we won't be."