London Welsh head coach Justin Burnell says his side made too many errors and missed too many tackles in their 52-0 Premiership defeat by Exeter on Sunday.
It was the club's first game back in the Premiership following promotion.
And Burnell has urged his side to learn from the experience if their top-flight return is to last beyond one season.
"We've just got to learn from our mistakes and there are a lot of mistakes to learn from," the 47-year-old told BBC Radio 5 live.
"The most frustrating thing is we got into areas but just didn't capitalise on it. Once that happens against a good side like Exeter, they will score against you."
|London Welsh coach Justin Burnell on loss|
|"The players are bitterly disappointed. 52-0 is not a nice score to see. We have got to learn from our mistakes and there are a lot of mistakes to learn from."|
In particular, Burnell says their tackling was not up to scratch but has promised his side will come back fighting against Bath on Saturday,
"That's life," he said. "That's what we chose. We fought hard to get into the Premiership and we will fight hard to stay in the Premiership.
"There were too missed tackles, the count was up in the late 20s and that is not acceptable. It's faster and heavier and we saw the speed today."
Burnell also rejected the suggestion that it was going to take time for their 25 new players in the squad to gel.
Welsh included nine new summer signings on Sunday at the Kassam Stadium, but Burnell says that was not a contributory factor.
"It was individual errors that cost us," he said. "We've got to get back into work, pump out our chests and keep smiling. It would be easy to hide away and not learn but we have to learn.
"They are bitterly disappointed. 52-0 is not a nice score to see."