Jose Mourinho suffered his first defeat in his second stint at Chelsea this weekend, as his side lost 1-0 to Everton at Goodison Park.
After the match, Mourinho lamented his side's lack of composure in the final third, and commented on the number of chances his strikers wasted.
However, he did not comment on the way his team defended, and especially the performance of one man in particular - David Luiz.
Since his big-money move from Benfica, the Chelsea faithful have been very taken with the comical Brazilian. He has scored some important goals and played a key role in their successful Champions League campaign. But is he a top quality central defender? The simple answer is no.
I do not doubt his footballing ability. His energy and enthusiasm is infectious, his technique is superb and his range of passing, with both feet, is excellent.
But you have to be much more than a good footballer, to be a central defender. You need to be intelligent, read the game well, understand where the danger is coming from, and what the best position would be to deal with it.
Sadly, Luiz fails on many, if not all of those fronts. His positional play is very naive, he often storms out of defence to start an attack and then it takes him an age to get back into position, when the attack breaks down.
If you look at Steven Naismith's goal at Goodison Park at the weekend, he was closer to the edge of the 18 yard box than he was to Naismith, who went on to head in from five yards out.
You could forgive Luiz for that lapse in concentration if it was a one off incident, but during his two-and-a-half-years at Stamford Bridge, it has happened on countless occasions.
As a central defender, he cannot cut it at Chelsea. Especially now Mourinho has returned. Historically, the Portuguese coach's teams are strong and reliable at the back, which allows the forward players a lot more freedom to express themselves.
However, with Luiz in defence, the central midfielders always have to be aware that he could move out of position and make a mistake, which restricts them from playing their natural game.
Luiz has shown on many occasions that he can perform well as a central midfielder, as his abilities do suit that role very well. But, with the amount of quality midfielders Chelsea have on their books, he might not get a look-in in that department.
If he continues to make mistakes, Mourinho will not put up with it for very long. John Terry and Gary Cahill are a much more balanced and effective partnership in that Chelsea defence, even moving Branislav Ivanovic inside would be a better alternative to putting up with Luiz in the position.
He is a very good footballer, but as a centre-back, he is nothing but a liability.
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