Wasps boss Dai Young admits his side got what they deserved in Saturday's 36-17 defeat to Saints at Franklin's Gardens.
Saints scored five tries as they secured a superb bonus-point victory on home soil.
It was their third Gallagher Premiership win in seven matches this season.
But for Wasps, it was more disappointment, as they have still not won in any competition since the final weekend of September.
And Young said: “It was really disappointing. Obviously sometimes you don’t get what you deserve in this game, but on Saturday we did.
“I thought Northampton were good and we were poor.
"It was a really disappointing performance.
“We were really lacking any sort of consistency in the way we played right across the board.
"We made fundamental errors that mean you are not going to win many games.
“There’s no answer or a magic cure, we’ve just got to work hard to turn this around and quickly.”