A frustrated Dai Young has pointed to a disappointing first-half performance after Cardiff left Brive empty-handed on Saturday.
The Blue and Blacks went into the final pool stage encounter with three consecutive bonus-point wins but they came unstuck in south west France.
Brive raced into a 19-3 lead, punishing Cardiff’s sloppy start to the encounter and while Young’s side battled back with tries from James Botham, Rhys Priestland and Jason Harries, they could not get over the line.
Young said: “We’re frustrated really. We’ve talked about how important a good start is and today we started really poorly.
“In the first 25 minutes I don’t think we got past two or three phases. We put a lot of pressure on ourselves, which gave them plenty of opportunities and we dragged that out for 35 minutes.
“We didn’t really cause them any problems, we didn’t fire any shots of our own and went in at half-time 17-3 down… and we a little bit fortunate to only be 17-3 down.
“We talked about putting pressure on them but we didn’t have entries into their 22 in the first half. So we put no pressure on them which is hugely disappointing.
“So we talked about field position and not playing too deep in the second half. Once we got field position, playing with a bit more intent, and being a bit more direct for half an hour, we were excellent.
“We got our noses in front and then started to play too much, which is disappointing. We should have just stuck to the blue print, which gave us success.
“I’m disappointed with our game management in the last 10 minutes, ultimately it ended up a two score game.
“We just needed to make it simple. We took a few quick taps inside our own 22, which I don’t quite understand. It’s disappointing and something we need to talk about and take learnings from.
“There were positive parts but we have to start the game better, we have to be far more accurate, pressurise the opposition and if we find something that works, we have to stick to hit.”
Cardiff had a fourth try from Aled Summerhill disallowed and Lloyd Williams crossed but was unable to ground the ball with the final play, that meant they finished outside the top two in Pool A.
Instead, they now have to wait until Sunday to learn which Heineken Champions Cup side they will face at the Arms Park on the weekend of March 31/April 1.
Young added: “We’ve got a home draw, which is pleasing and if we finished in the top two then we potentially had two home draws if we progressed.
“But we would have settled for getting out of the group and into the last 16, so we have to be happy with that.
"I always felt today was going to be a tough game but we made it tougher than it should have been.”