Mauricio Pochettino admitted troubled Chelsea's worst moments this season have been "so bad" after the Blues suffered their heaviest defeat in over five years.

Pochettino's side slumped to an embarrassing 5-0 loss at Arsenal on Tuesday to heap renewed pressure on the beleaguered Chelsea boss.

It was Chelsea's worst ever result against London rivals Arsenal and marked the fifth time this season they conceded four or more goals in a Premier League game.

In his first season in charge, Pochettino has failed to build a cohesive unit despite Chelsea spending over £1 billion ($1.2 billion) on new signings in the last two years.

Chelsea's hammering in north London came three days after they were arguably the better team but lost 1-0 to Manchester City in the FA Cup semi-final.

"We are capable of having amazing performances, and three days after, in extremes," said Pochettino, whose team are languishing in ninth place in the Premier League.

"Our standard is not sustained. The bad days, when we have bad days, we are so bad. Then when we are good, we are capable of everything."

Heavy defeats have become a discomfiting theme this season for Pochettino, who will face a struggle to avoid the sack if results don't improve.

Chelsea have lost 4-1 at Newcastle and Liverpool and 4-2 at home to Wolves, with the Arsenal humiliation exposing the flaws in Pochettino's defence after he made several changes from the FA Cup semi-final line-up.

"It was a great opportunity for different players to step up and say, 'we are here, it doesn't only depend on one player'," he said.

"But we didn't compete. I cannot blame the players. As a team we are showing this inconsistency. That is why we are where we are.

"The circumstances are bigger than the performance of the players. We cannot blame young guys that came here.

"That is the first time the defensive line has played together. It's not an excuse. I don't want to go again and again to talk in the same way.

"It's the circumstance we are living. From the beginning of the season we have suffered too many situations that are not helping."