Head coach Thomas Tuchel has criticised his Chelsea side for making too many individual mistakes, the latest coming against Everton on Sunday afternoon.
After Cesar Azpilicueta was dispossessed on the edge of his own penalty area, Richarlison subsequently scored to earn the Toffees a potentially-vital 1-0 victory in the Premier League at Goodison Park.
Chelsea have now posted four wins and four defeats from their last nine fixtures, and Tuchel feels that his team have become "too easy to play against" since the international break.
Speaking to BBC Sport, Tuchel said: "It is disappointing because over the last four matches we don't have enough points for what we want and it is concerning. We have one clean sheet over the last four matches and it is far too easy to score against us.
"We can't stop doing individual mistakes. We struggle to have repetitive top performances. Today was an OK performance but OK is not enough.
"We conceded in the first minute of the second half and it becomes more difficult,. The way we gave this goal away was absolutely unnecessarily. If we keep on giving goals away it ends up in the results we have had recently.
"We were not on the highest level. We trusted the team. Maybe we could have changed more. That is something I will reflect on personally."
Chelsea now sit just five points clear of fourth-placed Tottenham Hotspur with four matches remaining after Spurs eased past Leicester City.
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