Simone Favaro also crossed for the Warriors in the second half to put the game to bed after Dan Fish's score brought the Blues back into it, but it was the visitors who made more of the running late on with late tries from Ellis Jenkins and Macauley Cook handing them a losing bonus.
And while Townsend's side have games in hand on the sides above them in their bid to return to the top four, the former Scotland international insists what he saw on Sunday was not good enough to challenge the leaders.
"We would have been disappointed even if we had picked up a bonus point and sneaked one in the end," he told BBC Scotland. "Parts of that game weren't as accurate as we have to play and how we can play.
"In the first 50 minutes, we did some really good things, we showed at times how dangerous we can be. We showed a real determination in defence to compete for ball and we got a few turnovers in the first half.
"But we set ourselves higher standards than that. The last half hour, we played our poorest rugby and we need to be better, especially with Ulster and Leinster in our next two games.
"Both are at home but still very tough; both teams are in the top five and Leinster are in fantastic form just now.
"Players and coaches all realise that if we play close to what we did in this match, we won't win against Leinster. Our accuracy and focus - I was going to say work-rate but that was pretty good - will have to be much better next game."
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