Graham Potter said his Swansea City side had been dealt a "cruel" lesson after missed chances in one box and poor defending in the other contributed to a 3-0 defeat at West Brom.
The final margin of defeat was heavy, and gave little indication of the long spells in the game where the visitors had control and created a number of presentable chances.
However, all those opportunities were spurned.
Daniel James, Wayne Routledge, Nathan Dyer, Bersant Celina and Connor Roberts were all denied by Baggies keeper Sam Johnstone when they may feel they ought to have done better.
Roberts struck the post and Celina also missed a penalty - kicking the ball against his standing leg - after Mike van der Hoorn had been fouled by Craig Dawson trying to get on the end of a cross.
The hosts, meanwhile, claimed a first home win in seven games thanks to goals from Chris Brunt, Mason Holgate and Jay Rodriguez, all of which came from set-pieces that Swansea failed to deal with.
"In between the boxes we were really good, the better team. We created probably as many chances as we have created away from home, and even maybe at home," said Potter.
"The keeper has pulled off a couple of good saves, and the penalty is not a good moment for us.
"But we have not defended our box well enough and the result is not something we like, but there were positives in the performance.
"We won the ball back, created chances but the three goals are poor and we have to be better and take responsibility.
"If we had those chances again, I think we would score. It was one of those nights.
"I'm not sure anyone will have created so many chances here this season, but we have lost 3-0 and that is the madness of football.
"It was a bit cruel, we did not deserve a 3-0 scoreline, but if you don't defend your goal that's what happens."