Michael Ballack believes his former Chelsea team-mates' lack of mental strength is the reason behind the current malaise at Stamford Bridge.
Ballack was part of the Bayer Leverkusen side who inflicted a 2-1 loss on Andre Villas-Boas' men in the Champions League midweek - their fourth loss in the past seven matches. The German spent four years at Chelsea and says the mental fortitude which saw the club win six trophies during that period is now missing.
"We knew before the game they were in a difficult moment but it's only when you play against a team on the pitch that you see what is really happening," Ballack said. "We could feel it on the pitch every minute, especially at the beginning of the match, that they were not as strong as they normally are.
"Even when they were 1-0 up we could sense that, that they didn't have the strength mentally that they normally have. We felt that on the pitch."
Ballack also expressed sympathy toward the embattled Villas-Boas. The 35-year-old midfielder had five managers during his time at the London club, and has seen the ruthless dealings of Chelsea owner Roman Abramovich.
"I played four years for Chelsea and I know how quickly it can go," said Ballack. "I had a few managers in that short time. I know it is always difficult for the coach. But that is not just about the coach, it is about the players too. They have to get out of this situation."
"With every defeat you can see they are losing confidence. You have to get back to your roots, to square one, but with the ambitions they have of course it is harder and they are not matching them."