Despite earning a losing bonus point this defeat meant the Warriors finished as the lowest of the second-placed therefore miss out on a place in the Amlin Challenge Cup.
And after being left with just the RaboDirect PRO12 now on his calendar, Lineen admitted things need to change ahead of next season.
He said: "Some of the big-name players had big games, Sean Lamont was very good at full-back, Johnny Barclay made some cracking breaks and tackled his heart out, Chris Cusiter got the ball away well and also made some good breaks.
"However, we did not deal with the set piece and there were some individual mistakes which cost us.
"The interception try in the first half gave them a spark, then we did not deal with the rolling maul.
"We scored two cracking tries, they had an intercept and a rolling maul but it is the same amount of points and we have to learn that lesson."