However, tries from Gareth Davies, Kristian Dacey and Dan Fish saw the home side outscore Leinster in the final hour of the game and the home side were pushing for a try in the final minutes that would have secured two bonus points.
Blues eventually came up just short in an entertaining clash, but Davies was left proud of the reaction of his team to the early try burst from Leinster and the desire and ambition of his team.
He said: "The result was not what we want wanted. But in terms of performance, there was a lot of desire there. The intent of the way we were trying to play was fantastic.
"When you play teams like this, with the quality Leinster possess, you are going to have times when you are on the back foot. At certain moments we lacked accuracy and they capitalised on it, all credit to them for that.
"I was proud of the player's desire tonight and their 'want' to play was fantastic. This experience was tough but it will hopefully be the making of us in time to come.
"The ambition was good and, if we had four tries like we could have had, and there was a really clear cut opportunity in the first half, we could have pulled out a try bonus point and got something out of the game.
"It would have been great and it was a shame that the performance didn't warrant anything other than blood and guts.
"I thought the fans support tonight was superb and we now have one more game left in this series and we have to go away to Italy, play Zebre and win. Nothing else will do."