In search of the greatest goalkeeper

Rating a goalkeeper by the goals they concede doesn't paint the whole picture. Everything must be put into context, from he level of the team, their style of play to the number of shots they save and the number they face.

This considered, MARCA wanted to see who LaLiga Santander's best goalkeeper is. To do so we've considered all of the goalkeepers to have played at least 1,000 minutes this season, and have used players from other leagues as a point of comparison, taking OPTA and StatsBomb statistics.

Courtois on top, Ter Stegen struggles

First looking at the percentage of shots saved, Thibaut Courtois and Unai Simon look good. Real Madrid have conceded just nine goals, and the Belgian has stopped 71.11 percent of the 45 shots from inside the penalty area.

Marc-Andre Ter Stegen surprises though, and he's way below the median in terms of saving shots.

Aitor Fernandez, the octopus

Another name to highlight is Levante's Aitor Fernandez, coming in second with a 69.61 percent save rate.?It should be pointed out though that he has faced more shots than anyone else from both inside and outside the area.

How many goals should he concede?

Despite his high number of stops, Aitor had conceded a high total of 36 goals up until Round 24. In this era of football data, we can now measure how many goals a goalkeeper should have conceded in a similar way to how expected goals are calculated.

This is called Post Shot Expected Goals (PSxG), and Aitor's total is 44.6, almost nine more than the reality. That makes him not only the best in Spain, but also in Europe.

Oblak's case

Both Jan Oblak and Ter Stegen surprisingly have a negative balance in the PSxG differential.

Does this mean they aren't good? No. It simply means they're not doing as well as it seems when it comes to saving shots.

Oblak, for example, is the goalkeeper who has made the easiest shots across the top leagues.

This suggests that the reason he faces so few difficult shots is because of Atletico Madrid's good defensive setup, forcing opponents into shooting from unlikely positions.

Who is the best?

Based on stops alone, it's Aitor Fernandez. But there are more things to consider.

Combining a number of other metrics, including dealing with crosses and distribution, Aitor still comes out on top ahead of Unai Simon and David Soria.

Spain's goalkeeper

Kepa Arrizabalaga's delicate situation at Chelsea has the debate around Spain's No.1 shirt building again. Looking at the stats, it's no surprised that Frank Lampard has opted to leave him on the bench, although Chelsea's defence haven't helped him.

According to PSxG, he has conceded four goals more than he should have. David De Gea is likely to take the spot, but he's not at his best level this season according to the data and the door could well open.

Alisson Becker stands above the rest

It's not a shock that the Brazilian is the best around. He's saved 100 percent of the shots he's faced from outside the area and 76.9 percent of those inside it, though it should be noted that he is the 'keeper who has had the fewest saves to make at 47.

Second place is a surprise and that's Dijon's Alfred Gomis. He's only conceded 20 goals and should have conceded 25, regularly stopping complicated shots but from inside the area he's saved 77.42 percent of the strikes he's faced

Juventus' Wojciech Szczesny completes the podium. Like Alisson he's stopped 100 percent of shots from outside the area and 68 percent of those inside, boasting a PSxG differential of 5.5.