Luiz's World Cup display proves Jose Mourinho right to sell the Brazilian

There were 50 million reasons for Jose Mourinho to be celebrating Germany's historic beating of Brazil in their World Cup semi-final this week.

Chelsea's sale of David Luiz to Paris Saint-Germain for £50 million was already being hailed as phenomenal business on the club's part, and on the back of his capitulation against the Germans, it's even more so.

Let alone being the sale of this century, it's possibly the sale of all time.

Luiz was woeful in Belo Horizonte. From the 11th minute, when Thomas Mueller's opening goal went in, the former Chelsea man had the look of a boy lost.

His head went, he lost any sort of composure and so came with it the erratic challenges and decisions that so frustrated Mourinho in the one season he spent with the Brazilian as part of his playing staff.

Wearing the captain's armband in the absence of the suspended Thiago Silva, so much more was expected of him.

For a moment, Luiz seemed he would live up to the expectation ahead of kick-off. Stood next to Julio Cesar, passionately signing the Brazilian national anthem while holding Neymar's shirt in tribute to his injured comrade, he looked a man ready to step up for his country.

Only, he crumbled when he was needed most.

When a club pays £50 million for a player, the minimum expectation is for him to at least have the discipline to control his emotions in times of need, to use his experience to get through.

Then, there is the question of his ability, to make the right decisions and maintain composure to influence games. It's schoolboy stuff.

For Luiz on Tuesday night, it was the opposite. If he has any of those qualities, they evaded him in an instant.

Indeed, his performance—and that from the rest of his teammates—quickly went from tragedy to farce in just 20 first-half minutes as the goals reigned in for a ruthless Germany.

Brazil were shell-shocked, on the ropes, being beaten to a pulp.

And where was Luiz, their £50 million captain? Well, as the below heat map from Squawka shows, anywhere but where he was supposed to be in the heart of the defence.

He went AWOL, his lack of discipline proving decisive as Germany eventually secured a 7-1 victory.

Gary Cahill may lack the skill and adventure that Luiz often demonstrated in his Chelsea career. He may even lack the qualities of a "geezer" that so endeared Luiz to the Stamford Bridge crowd.

He doesn't need them.

Cahill's job is a simple one: to defend the Chelsea goal alongside John Terry, ensuring the Blues score more goals than they concede.

It's what defenders do.

As a player, Cahill is no thrills in many respects, but as a defender, his quality is of the highest order.

That's why Mourinho fast-tracked him to become Terry's permanent partner last season, leaving Luiz on the sideline to watch.

Brazil's defeat to Germany confirmed Mourinho's wisdom all the more.

Given the level to which Joachim Low's team performed, it's likely they would have progressed to the final. They looked unstoppable, but never would they have imagined it would be so convincing.

Luiz certainly helped.

The PSG hierarchy must now be seriously questioning the decision to splash out such a significant sum on him.

Luiz is far from a £50 million player, and given the sanctions they have had imposed by UEFA for failure to adhere to Financial Fair Play rules, it makes his transfer all the more remarkable.

Laurent Blanc was seeking a partner for Thiago Silva, of which Luiz is. He's a No. 2, so for Chelsea to have not only demanded £50 million, but got it, is nothing short of genius.

PSG have fallen into the trap Chelsea themselves have done on many occasions. The Ligue 1 champions paid a premium for a name, not a defender, and they will be counting the cost for some time yet.

Cue the memes, tweets and punch lines that Mourinho and the Chelsea board need to be arrested for having committed daylight robbery.