Jim Mallinder was left frustrated by key decisions as Saints endured late anguish at Bath.
But the director of rugby refused to lay the blame for the 32-30 defeat solely at the door of referee Wayne Barnes.
Saints were eventually beaten with the final kick of the game as Rhys Priestland landed a match-winning penalty for the home side.
But it was earlier decisions that disappointed Mallinder and his men.
They felt there was a clear forward pass in the build-up to Chris Cook's try, which helped to take Bath into a 29-23 lead.
And there was also annoyance that Barnes did not award Saints a penalty try, as he had done for Bath in the first period.
"There were some big decisions," Mallinder said.
"We conceded a penalty try - fair enough - but then we had a five-metre driven maul and we were heading towards the line. It got brought down and they (prop Kane Palma-Newport) got a yellow card for it.
"I don't think there's actually a lot of difference between the two incidents.
"There were lots of really close decisions, but we won't use that as an excuse and we need to look at our game as well.
"Certainly, we look at the positives of coming back and our attack in the second half, but defensively we weren't very good in the first half, conceded a real weak try to (Semesa) Rokoduguni, and some of our exits weren't very good at all."
On what Saints felt was a forward pass from Ben Tapuai in the build-up to Cook's try, Mallinder said: "It definitely was.
"At the time it looked forward, and then looking straight away at the computer, it is forward.
"We've got technology, we needed to use it for any doubts like that.
"We did ask the question, but the referee decided not to look at it.
"It was a big decision in the end."
Saints had fought back superbly after falling 22-9 down early in the second period.
Tries from Ben Foden, Api Ratuniyarawa and Jamie Gibson, allied with the flawless kicking of Stephen Myler, gave them a 30-29 lead.
But Priestland stepped up to puncture the fightback.
"We talked beforehand about them having a big pack and we wanted to play fast and for the full 80 minutes," Mallinder said.
"We've had some good second half performances recently, our fitness has showed, so even at half-time, when we hadn't been playing particularly well, we knew we were still in the game and so it proved.
"But there were some big points, some big decisions and unfortunately they didn't go our way tonight."