They certainly were stunned at Old Trafford when Jay Rodriguez led home although United had to draw keep the title race alive.
The win was West Brom's first since a 2-0 success over Brighton on 12 January and only their fourth all season.
He said: "We've got faith in one another, the players, the staff. Things have gone a bit by the wayside this year".
In the midst of winning four titles in five years, this was an increasingly sophisticated United side, reflecting Ferguson's desire to thrive in Europe as well on domestic soil.
The West Brom fans didn't miss a chance to make light of the situation on a day of disappointment for the home side.
"Everything was slow, one more flick, trick, turn".
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There was enough in Sunday's performance to suggest caretaker manager Darren Moore should stay in charge.
West Brom finished with their backs to the wall but had chances of their own, and Jake Livermore had earlier tested David De Gea with arguably the best opportunity before the break. "You have to be consistent, not just one wonder season", Giggs said.
Winning the title by two points from Chelsea, in the Champions League United saw off Barcelona in the semi-finals and, in the final, beat Chelsea on penalties in the Moscow rain.
"I knew that sooner or later they would be (champions) and if I was in their position I would be very upset if someone said they won the title because Manchester United lost against West Brom".
"I'm proud for players and staff and way they have acquitted themselves today".
Paul Pogba, the two goal hero last week, was substituted in the 58th minute after a poor display in which he also picked up a yellow card.
But, just a week after spoiling City's title party by beating their local rivals 3-2 at the Etihad, the way United abjectly gifted the title to their neighbours will sting. He name-checked eight games - Milan against Napoli, Schalke against Borussia Dortmund, Celtic against Rangers, P.S.V. Eindhoven against Ajax - but not the one that could decide the title.
But Jay Rodriguez's goal at Old Trafford sent the EPL trophy to the other side of Manchester for the third time in seven seasons.