Edouard Mendy says consistency is behind Chelsea's recent woes.
The Blues were thoroughly outplayed in Tuesday's loss to Leicester City, their fifth defeat in eight league games.
And Mendy says Chelsea must start playing a consistent 90 minutes if they want to turn results around.
Asked what was missing from his side, Mendy told the club's website: "What we are missing at the moment is consistency, being good for the whole match.
"We often have a bad patch, concede a goal and it makes it too hard to recover. We need to find more consistency in matches to be able to get past this level of team.
"It's difficult to explain because we were in good form and then we got into difficulty. It happened very quickly. We need to concentrate on the return phase now and getting near the levels we were at.
"It's up to us to rectify the current situation and above all show more. We have to stay together and stay as positive as possible during this delicate moment."