For all the problems John Terry brings to Chelsea, his absence causes difficulties too. For all the hopes that Chelsea might be able to move beyond their tainted captain, they seem to need him on the field as much as they ever have.
Since Terry has been out, first with his four-game ban for racial abuse and then with a knee injury, Chelsea's results have slipped. They have not won for four league games, and were well beaten 2-1 at West Bromwich Albion on Saturday. Manager Roberto Di Matteo admitted afterwards that they miss Terry and need to improve in his absence, which is certainly true given their week ahead.
On Tuesday Chelsea play their hardest and most important game of the season so far, away at Juventus. Their future in this season's Champions League will be at risk. Lose, and elimination is likely. They will also have to go to Turin without their captain.
Of course, on their famous Champions League campaign last season, there was no Terry for either of their finest moments: the second half in Barcelona, or for the final itself in Munich. But Chelsea are demonstrably a better side with him. He has been their dominant defender for more than a decade, and that creates a pattern which is difficult to break.
There are ways in which it would be easier for Chelsea if Terry was no longer there. His continuing as captain is understandably unpopular in some quarters outside. But, on the pitch, Chelsea are worse off without him.
Di Matteo's side are currently on their worst run of the season. They have won just two of their last seven games in all competitions; a 5-4 extra-time defeat of Manchester United reserves in the Capital One Cup and a 3-2 stoppage-time victory over Shakhtar Donetsk. Such is their slide that Di Matteo is considering personnel changes and a return to the pragmatic approach he adopted when he first took charge – before Roman Ambramovich's desire for more attractive play began to be satisfied.
What he cannot do, is call on Terry. The defender has only completed one of those last seven, the 2-1 loss in Donetsk which started it all.
He was suspended as his team-mates lost 3-2 at home to United and drew 1-1 at Swansea City. Terry was not picked for the 3-2 victory over Shakhtar, although he probably ought to have been. Returning against Liverpool, Terry scored and went off injured before Liverpool equalised.
That knee injury kept Terry out of Saturday's defeat at The Hawthorns in which Gary Cahill and David Luiz were pulled apart by Shane Long and Peter Odemwingie. Luiz let Long peel away from him at the far post for the first goal, after a cross was welcomed through.
For the second, Luiz allowed a cross from the right and Odemwingie beat Ryan Bertrand at the near post to head Albion back in front.
These goals, from barely contested headers from stoppable crosses, are of the sort that Terry simply does not permit to happen on his watch. For all of the qualities of Cahill and Luiz, Chelsea are a different and lesser side without Terry.
On Saturday, they were also angry. Luiz said: "We were upset and angry. There were raised voices in the dressing room but that is normal. This is a big club and we don't like to lose games.
"We missed the moment but all we can do now is look ahead. The future is Juventus. They are just one point behind us. This is the most important game in the group.
"In the Champions League we have a great opportunity to qualify even though Juventus and Shakhtar [Donetsk] are both great teams."
Cahill and Luiz are both quicker than Terry. They both have a better first touch and sense of a pass. They are both more comfortable with the ball at their feet. They both have a much better shot. But defending is about grit as much as grace, and about collective qualities as much as individual ones.
Chelsea will be facing excellent opponents tomorrow night, who caused them problems in the 2-2 draw in Stamford Bridge in September. The movement of forwards Sebastian Giovinco and Fabio Quagliarella is excellent, as are the runners from midfield. If Chelsea lose, their survival in the competition will be in doubt.
Di Matteo knows that they must find a way. "Clean sheets certainly give you a chance to win games and we certainly have to improve on that side," he admitted after Saturday's defeat. "Defensively we just weren't good enough. Of course we miss John. He is an important player for us. He gives us a lot of confidence at the back and in general to the team.
"I think as a team we have to be better defending. You don't defend with one player – you defend with the whole team, like you want your whole team helping when you are attacking as well. It is a defensive organisation on the pitch that we need to look at and, as I said before, maybe I have to do some changes.
"We have got bodies in midfield – the 4-2-3-1 system really helped us last season after the change [of manager] but maybe in terms of personnel we have to do something different.
"It's a shame that John is injured - but we will have to do without him until he comes back – and improve."
They certainly must if they are to get the draw they need tomorrow. Beyond that Manchester City come to Stamford Bridge on Sunday and Sergio Aguero and Carlos Tevez are no respecters of messy defences. Chelsea need to find a safe combination without Terry, not just for the future but for now.
Champions league: Eye on the opposition
Juventus prepared for Tuesday's Group E visit of Chelsea with a goalless draw at home to Lazio on Saturday.
The leaders, who lost their previous home league game against Internazionale earlier this month, dominated proceedings, but could not beat a dominant Federico Marchetti in the Lazio goal. Sebastian Giovinco went close and Leonardo Bonucci hit the bar but Juve missed the suspended Andrea Pirlo and injured Mirko Vucinic.