"It was an absolute giveaway, but we were very poor and lucky to be two goals up, because West Ham were the better side," Ferguson said. "It was a ragged and tired performance. We didn't deserve to win, but having been two up it's disappointing to have thrown it away."
Ferguson blamed his side's midweek European heroics for their below-par display.
"European games always seem to take their toll," he said. "We lost three players today and after the game against Juventus we lost four. You can't keep on changing a team in League matches like that.
"I sent on Phil Neville to secure the result but it was a complete giveaway. There's no more to be said."