Speaking to BBC Sport, Frank Lampard said: "Not good enough first half, that's what confirms the result. Much better second half, but not good enough first half.
"We were too nice to play against in all aspects in the first half. In the second half we played much more like a team that has a threat up top.
"In the first half we were too easy to play against. It's tough because you want to win games, but it's our job, we'll work on it."
Chelsea conceded three goals against Arsenal in the first half on Wednesday before pulling one back after the break at the Emirates.
The 3–1 defeat means that the Blues have now lost all six games under Lampard with five games left to play in the 2022/23 Premier League season.