Chelsea manager Xabi Alonso criticised his players' game management after they were humbled 3-0 at Brentford, while defender Levi Colwill said his team were bullied at set pieces.
Brentford scored three second-half goals to ease past Chelsea, with Jaidon Anthony, Igor Thiago and Fabio Carvalho all scoring.
It was the third successive Premier League game in which Chelsea failed to win, having lost to Arsenal and drawn with Hull City last weekend.
While Chelsea have looked a threat in attack in their previous games, scoring 10 goals, defensively they look less than solid, with the three goals conceded at Brentford meaning they have been breached 12 times already.
Alonso is only the sixth manager to concede two or more goals in each of his first five Premier League matches in charge.
"I would say that we have dropped our consistency, our competitive mentality needed in the second half," Alonso said.
"I'm disappointed at the end with the second half and the result," Alonso said.
"This is not enough to compete in the Premier League, not to be able to go for the 90 minutes. This is why today we were punished. It's not about talking or looking for excuses."
"You know that the small details can be decisive. You don't have to give advantage in these kind of games. But it's about 95 minutes and we have not been able to keep that level throughout these few games in the start of the season and it's something that we'll have to do better."
Colwill said on Sky Sports that Chelsea were being "bullied" at set pieces. "It was tough. Maybe we overexposed ourselves [at 1-0 down] and they hit us on the counter-attack, which they're so good at," Colwill said.
"Second half we weren't good enough. We've got a lot to work on over the international break. Maybe at times we've been bullied [at set-pieces] and we have to improve at that. We can't rely on our front three to pull us of danger; we all need to help each other. We've got a lot of room to improve."
Alonso agreed with his captain, saying: "It's not just set pieces, but in duels, defence, in build-up, in and when we conceded first, but still we were in the game; but when you lose shape, you are out of control.
"So to be able to understand the game, to know what it takes to be competing until the end, is a process. It takes time for them to feel that. And at the moment we are not feeling it fully to compete for the whole game."
Victory means Brentford remain unbeaten in the league heading into the international break, having won twice and drawn three.
"I was really looking forward to the game – the opposition have been setting up in a respectful way to nullify what we do," said Brentford boss Keith Andrews.
"I felt there was a performance bubbling, the approach was focused and in the second half we showed what we are. There's a really nice connection between the fans and players. We're enjoying the journey we're on. I love feeling that energy and how we play. We need to consistently evolve how we play."
The win moved Brentford up to third on nine points while Chelsea remain seventh on seven points.
