By the time Liverpool equalised on Sunday, Chelsea should have had the game won.
They ought to have been at least two or three goals to the good, with Oscar, Juan Mata and John Obi Mikel all missing good chances.
And the way Chelsea are defending at the moment, 1-0 never seems to be enough of a lead because they just cannot keep a clean sheet.
At the start of the season Roberto Di Matteo’s team looked great going forward and secure at the back.
There were four clean sheets in the first five league games – but there have been none in the six since then.
So what has changed? It is hard to escape the conclusion the absence of John Terry has been crucial.
In the four domestic games for which he was suspended, Chelsea conceded a total of 10 goals.
And some of the goals have been so basic.
The two scored by Manchester United in the first few minutes of the league game at Stamford Bridge saw United carve through the left side of Chelsea’s back line, where a lack of cover from midfield left Ashley Cole badly exposed.
And the two goals Shakhtar Donetsk managed at the Bridge – almost exact replicas of each other – both saw Willian wander unmarked into the centre of the penalty area, free to stroke the ball home unchallenged.
Against Liverpool, I thought Luis Suarez had been similarly unmarked as he headed home from about a yard out.
Of course I later discovered the reason Suarez had nobody challenging him was that he had pushed Ramires.
But that raises its own issues.
Why was Liverpool’s main goal threat – some would say only goal threat – being marked by a small midfielder like Ramires?
Admittedly the two players are similar in stature but would he have been able to push Branislav Ivanovic or Gary Cahill over so easily? Of course not. So why wasn’t one of them marking Liverpool’s centre-forward?
The current Chelsea will never be as secure at the back as Jose Mourinho’s team, as they play a different type of football.
But one statistic shows how stark the difference is.
When Carlo Ancelotti was sacked and replaced by Andre Villas-Boas, Petr Cech had kept a clean sheet in more than half his games for Chelsea – 159 in 313 matches over a seven-year period.
Since then he’s played 74 games and kept just 24 clean sheets – roughly one every three.
I am not blaming Cech for that – he’s largely been excellent in that time. It’s more an illustration of the defensive performance of the whole team.
And if Terry’s knee injury rules him out long-term I fear we could continue to ship goals.
We’ve managed to outscore Tottenham 4-2, Manchester United 5-4 and Shakhtar Donetsk 3-2 in the past month.
But it can’t always be like that and 1-1 draws in games we’ve dominated against Swansea and Liverpool have shown what can happen when we don’t kill teams off.
The bottom line is when you can’t keep a clean sheet you need to take your chances.
James Clarke is the author of Moody Blues: Following the second-best team in Europe
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This post was last modified on 12/11/2012