James Keene and James Hayter fired the Cherries to a surprise 2-0 win at Griffin Park, with Allen holding his hands up.
"I prepare the team, I pick the team and so it's my responsibility what goes on on the field," he said.
"We never got hold of the ball or put them under any pressure. It was a poor display but I'm not going to criticise any one area because we are a team and we win together and lose together.
"The players are down at the moment but they are highly-driven individuals and they will bounce back."