Chelsea produced their poorest performance of the season at Wembley, finding themselves trailing 2-0 after just 16 minutes thanks to goals from Dele Alli and Harry Kane.
Sarri labelled Chelsea's performance a "disaster", acknowledging he saw little way back after Kane's goal despite having 74 minutes left of the game.
However, David Luiz has revealed Sarri's unexpected post-match reaction, with the Italian apparently calmer than after some of Chelsea's wins this term.
"He has been, many times, angrier when we've won," the defender told reporters. "It's true. Nobody is happy, of course, the coach is not happy.
"He always tries to do his best for us, and we try to do our best for him. Of course, he's not happy like every single player is not happy.
"But I think it's good for us to understand – to remind us – that the Premier League is never easy. It's not easy to win any game.
"Like I said, we didn't play well. We played really badly, we didn't have the same intensity as in the other games.
The Blues are back in Premier League action three days later in a London derby against Fulham and Luiz hopes they can secure three points to close the gap on their title rivals.
"The good thing is that we have another game next week, so an opportunity to recover and gain some points," he added. "Then, soon, we have [Manchester] City, a tough team, the top club in the table, so we can try and make the gap a bit smaller then.
"It was our first loss, but even if you win you have to analyse and improve. That's the only way to success.
"We will analyse as soon as possible what we did badly, to improve it in the week, and to try to do better in the next game."