Frank Lampard says Chelsea's disappointing run of form which has not seen them keep a cleansheet in eight games could be down to "lack of concentration" on a collective aspect.
He has also questioned the team's Mentality as he believes there are some experienced heads in the group.
"It’s a mindset. Every game’s different, but you have to have a mindset within the group, on the pitch, because those things are not unexpected," Lampard told the club's official website.
"We spoke at half-time, for instance, about what may happen, what they may do, and then you rely on the players on the pitch. So together they have to solve issues. It’s been a problem.
"It’s always collective. As a group, we can’t be happy with it. This group has young players and experienced players and you can’t be happy when you have moments when you concede like that.
"I don’t think it matters how young you are, it isn’t naivety, I think there is a concentration issue. We have to concentrate even more.
"Games change with goals – the atmosphere in the stadium, the feelings of the other team. Sometimes you need to dig in and concentrate that little bit more as a group. We’ve been tested with that a lot and we talk about it a lot, but the players have to find a solution on the pitch."