Chris Boyd says Saints would not have been satisfied with a draw at Bath.
And the boss admits his team's start to the new Gallagher Premiership season has 'not been good enough'.
Dan Biggar missed a difficult conversion with the final kick of the game as Saints suffered a 17-15 defeat in wet and windy conditions at The Rec.
Bath just got over the line in a scrappy game, in which neither side impressed.
Cobus Reinach and Tom Collins scored for Saints, but their late fightback from 17-7 down fell short.
And Boyd said: "We're disappointed we only came away with one point. It's a disappointing performance really.
"Even if that conversion had gone over and we'd got a draw, we wouldn't have been happy with that performance.
"We overplayed a little bit in the first half, tried to play too much through the middle of the field and then didn't manage to control our share of the ball, especially in the set piece.
"We've been very good in the scrum and lineout but in this game it didn't function to where we'd want it to.
"It was tough conditions and they contested the ball hard. They've got a big pack and we just didn't do well enough.
"It was 7-7 at half-time and we'd had a lot of the game to come out with it being drawn.
"To concede that seven points for their first try was disappointing.
"The margins are pretty small in competitive sport. We had plenty of opportunities to win that game and didn't. We have to work out why that is, correct it and do better."
Saints have lost to Gloucester, Saracens and Bath, with their only win so far this season coming at home to Harlequins.
And Boyd said: "It's not good enough. We've had one win from four games and we've been in all of them in patches, but we haven't come out on the right end of the scoreboard and we haven't dominated them as we'd have liked to.
"We've just got to keep working hard and hopefully the performance will come."