Head coach David Ripley reflected on a real 'low point' for his Steelbacks side after they were smashed by 80 runs at Headingley.
Yorkshire Vikings cruised to victory, bowling Northants out for just 107 after earlier posting 187 for seven.
Northampton-born David Willey was the destroyer-in-chief during the reply, taking four for 18 from his four overs.
Only Tom Sole, who racked up an unbeaten 41, provided any sort of resistance.
And Ripley said: “We didn’t field well, we didn’t bowl well, we didn’t bat well. When that happens, you’ll struggle to make an impact on a game of cricket.
“It was a low point. We’ve had a few of them in the competition, and we haven’t played particularly well. This feels particularly disappointing.
“The good news is that it’s not our last game. If we turn around tomorrow (when the Steelbacks host Worcestershire) and play better than that, we’ll offer the supporters something better than we did to anyone who made the trip here.
“We dropped three catches. We held a couple of good ones, but dropping three catches is too many.
“We got 19 off the first over and were out of the blocks very quickly, but four or five overs later the game was over.
"Losing five or six quick wickets, you’re never going to take down a score of 180 plus.
“We didn’t make Yorkshire work hard enough for their runs, either. There were too many square boundaries and too many boundaries the batsman’s not had to work hard to find.
“We were just poor, and the players are disappointed.”
It was a dead rubber as neither Northants nor Yorkshire can make the Vitality T20 Blast quarter-finals.
But it was still a satisfying night for former Steelbacks star Willey.
“That was very typical of the way we’ve played in the last few years," said the England all-rounder. "We either blow teams out of the water or lose. There’s no getting across the line in tight games.
"That’s where we’ve got to be better. If we get across the line in tight ones, we might have qualified.
“It’s nice for the fans who’ve come to our last home game that we’ve put on a show. But, ultimately, it’s disappointing that we’re out of the competition.
"It was a dead rubber after we’ve not played very well throughout.
“It’s been a while for me (wickets). I lost it a bit after I got out.
"I’ve been poor with the bat this year and have probably not bowled as well as I’d have liked either.
"So I came out more fired up than I usually am, and I seemed to get a bit out of the pitch bowling shorter than my usual length.
"They tried to hit to the short side and couldn’t get hold of it. I got some reward. That’s T20 cricket.”