Harlequins director of rugby Conor O'Shea was frustrated after his side went down to their third defeat in five Premiership starts, losing 18-13 at London Irish.
For 60 minutes, Quins were the better side but two tries in quick succession from Blair Cowan and Alex Lewington saw the game turn in favour of the Exiles.
"In the first half we had nearly all the territory and possession but we had inaccuracies all over the place," said O'Shea. "I'm really frustrated by our performance as you can't go out and play with such lack of precision and control."
Danny Care was introduced as a replacement for Karl Dickson after 60 minutes and scored Quins' only try with a 25-metre solo effort but O'Shea shrugged off suggestions he should have played from the start.
"Care is an individual genius but Dickson and he are both England squad members and there is little to choose between them," he said. "Karl showed a lot of control and the responsibility for the defeat lay with the outside backs who had enough space to go round the opposition."
Quins also lost Chris Robshaw midway through the second half but it was nothing too serious, with O'Shea reporting: "Chris informed me at half-time that he had a knock on the head.
"He wanted to give more but I could see he was struggling so I replaced him."
Irish director of rugby Brian Smith conceded that despite the victory his side were not at their best.
"It was by no means a perfect performance but we found a way to get over the line," he said. "Every time we had a hurdle we found a way to get over it and I am very proud of the squad.
"It was a really courageous performance, especially after we lost Kieran Low after three minutes. We knew that they would throw the kitchen sink at us but you don't beat Quins by surprise or chance so we deserve a lot of credit."
It was 6-6 at the interval but Quins should have been ahead after Shane Geraghty opted to run a penalty award just before half-time instead of taking a simple three points.
"Shane is all ambition, it's very easy from the stand but at half-time I said that we needed to play in their half and take the points as we had a couple of chances to kick penalties in the first half but chose not to do so," said Smith.