Gary Cahill believes Chelsea's busy schedule this season has diminished Rafa Benitez's impact at Stamford Bridge.
The Blues will face Russian side Rubin Kazan in the quarter-finals of the Europa League just four days after hosting Manchester United in an FA Cup quarter-final replay.
European duties, the Club World Cup and a semi-final appearance in the Capital One Cup have given Chelsea the busiest fixture list of any side in the Premier League this season and Cahill insists Benitez was never given time to settle in.
"I think we know a lot more about what he expects of us now," Cahill told the Telegraph. "He is really thorough with the way he wants to play and his tactics. But it is difficult because of the amount of games we are playing.
"I can't tell you how many times we have everybody out for a full session. We have games, half the lads who didn't play have to train, the other half can't, so to get the full group together on the training pitch doesn't happen very often and that is very difficult for the manager.
"People criticise you if you say you are tired, and we know have to get on with it because the fixtures are there. But all I am saying as a general fact is that players do not go into every game feeling 100 per cent fresh, it is impossible.
"At a big club every single game is so important, but you might be going in 60-70 per cent fresh through no fault of your own. Everyone is trying to recover but you just don't have the days. It is not an excuse, but it is a fact."
Midfielders Eden Hazard and Oscar have been influential since joining the Blues last summer, but Cahill expects them to make more of an impact during the latter stages of this season as Chelsea look to secure a third-place finish in the Premier League.
"Eden, Oscar, they are fantastic players. These lads are the future of Chelsea. They are phenomenal footballers," Cahill said. "But it takes a little time to adjust to this league. So I don't think we are a million miles away. We have just slipped up a couple of times in situations where you would not expect us to.
"We are in a position that if we win we can get what we want. But games like West Ham are vitally important and there are teams on our shoulder going well as well. We have thrown away so many points this year. It's just that consistency we are after."