Coach Ian Davies described the Cornish Pirates' second-half performance in the win against Doncaster as 'rubbish'.
Pirates were 36-11 up at half-time after two Drew Locke tries and one each for Ian Nimmo, David Docherty and Ceiron Thomas.
But the Pirates conceded three second-half tries and former Redruth man PJ Gidlow missed a gilt-edged chance late on to give Doncaster the win.
"In the second half we were rubbish," Davies told BBC Radio Cornwall.
"That's something we can't be if we're going to see ourselves as pushing for the play-offs at the end of the season," he added.
Davies said the Pirates had to to improve if they are to repeat last season's success when they reached the play-off final.
"As promotion candidates we've got to be clinical and after the first 40 minutes when you're 36-11 up Doncaster should have been out of sight.
"We allowed them back into the game and that's not a top four side's performance in that second half," he said.
The Pirates moved up to fourth in the table after the win.