Stephens determined to get back to basics raced into a 2-0 lead after a brace from Glenn Murray but they left Craven Cottage with nothing after a disappointing second-half display.
They conceded four goals as Fulham boosted their chances of survival and moved nine points behind Chris Hughton’s men.
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Stephens concedes his team let themselves down but he has urged them to move on ahead of the meeting with Watford.
He told the club’s official website: “It thought we played well in the first half and deserved our lead at half-time. But we then went away from what we were doing in the first half. “They’ve got a lot of quality in their team and they showed it after the break. It was all our own undoing in the end. “It was the basic stuff, having a higher line, keeping the ball — everything we did in the first half to get the lead. When you go away from doing those things, especially away from home, you’re going to get punished.”
