Gerhard Struber criticised his Bristol City team for giving away cheap goals in their home defeat by Watford.
The Robins head coach told BBC Radio Bristol: "I am really frustrated and we expected a different result in the end, and a big loss is really painful.
"The control of the game was good, but some small details such as decision making... we were not lucky with the last decision that we did, and how to bring a player into a better position with a higher chance to score.
"Then how we gave away the goals was really cheap and it is really hard to describe. It is all small things - typical Championship.
"When you want to be in the play-off spots you have to win games in a row more and more times, and we must be honest with ourselves that this is a gap.
"We have to be better and we have to improve, how we bring a clean sheet home and how we score on a different level."