He thundered: "I'm extremely angry".
There is nothing more humiliating for a player than to hear his manager talking in the way Maurizio Sarri did after this Chelsea defeat.
"I'm not saying that Chelsea is an easy team to play against, but it's an easy team to analyse". And this is something I can't accept.
Arsenal are six points adrift of fourth-placed Chelsea and a defeat at the Emirates would not do their quest to finish in the Champions League spot though the league any good.
"I don't think a player at this level can be afraid to face up to their responsibilities". But it appears we still have this issue.
"I don't want to be thinking about it every day, especially as I find it really boring".
"I want to talk about tactics but it would appear this group of players are very hard to motivate".
The Chelsea manager, who had a career in banking before taking up coaching full-time and didn't work in the top flight until he was 55, ripped up the rulebook after his side's 2-0 Premier League defeat at Arsenal on Saturday.
"We made silly mistakes", he added. That's down to the type of players they are, their characteristics.
"People understand why I had to move", he explained.
Koscielny has struggled since returning from his ACL injury which kept him out for nine months in a shaky Arsenal defence, however, the Arsenal skipper turned back the clock today with an outstanding performance.
"If the Chinese clubs are interested in (Marko) Arnautovic then they should be interested in Ozil".
Why did Sarri lash out at his players?
Asked if he is the man to revive Chelsea, he replied: "Yes, absolutely".
"Honestly, I don't know what is going on". From a technical point of view the two teams were pretty much on the same level today.
"But what we need to become is a team capable of adapting, a team that can perhaps suffer for 10 to 15 minutes during the game but then play our own football". We have the players. "Instead, we were playing, at some stages, with seven or eight touches".
"This is the sort of thing that we don't want to happen".
Arsenal doubled their lead in the 39th minute when skipper Koscielny mistimed an attempted header but the ball came off his shoulder and beyond Chelsea keeper Kepa Arrizabalaga. We have to analyse the game and improve quickly because there is no time to think.