Goalkeepers Season Review Part 2: Aerial Command

In the first part of this season’s goalkeeping review I analysed the shot-stopping ability of the Premiership keepers. For the 2017/18 season review that was all we could do with the data available, but with the detailed amount of information we know have courtesy of ORTEC Sports, we can also map goalkeeping performances when it comes to dealing with crosses and distributing the ball to their teammates.

This second part of the review will look at which keepers are the most dominant in their own airspace.

Aerial Command

A shot-stopping analysis is fairly straight forward as there is a clear objective to measure: the ability of a goalkeeper to save a shot. When it comes to ‘aerial ability’, it becomes a little less clear-cut. A goalkeeper can’t – and shouldn’t - be expected to come for every high ball that comes into their area; sometimes the ‘right’ thing to do is to stay on the line, depending on their distance to the ball and the position of their defenders and the opposition players. Then again, a keeper that regularly comes and claim a high ball can be of very high value for their team, relieving pressure and recapturing possession of the ball.

There is also the available data to consider. Every pass in a game is given several attributes by ORTEC, including whether it’s defined as a cross and a high ball. For this analysis, I’ve concentrated on all passes labelled as a high cross where the following action on the ball occurred in a specified area within the penalty box. I’m also including all high passes into the same area that came directly from a corner, throw-in or a free-kick.

The goalkeepers are measured on how many of these high crosses they intercepted (including being awarded a free-kick after an ‘aerial duel’ challenging for the cross). The last piece of data included indicates whether the goalie caught or punched the ball during this interception.

What the data won’t tell us is how many times a goalkeeper went for a high ball and completely missed it or indeed whether it was the right decision to not come for the ball. But this data should give us a pattern of how aggressive and successful the goalkeepers are in claiming high balls and whether they prefer catching or punching when they do. I’ve labelled these attributes ‘Aerial Command’.

Pitch Graph.PNG

I’ve also divided up the areas in which the goalkeepers’ influence are measured. First, I restricted the analysis to high crosses to the area the width of the six-yard-box up to the penalty spot. I then split this area into two: an ‘Inner GK Area’, covering the width of the goal inside the six-yard-box  and an ‘Outer GK Area’, which covered the space between the post and the edge of the six-yard-box, in addition to the space between six-yard-box and the penalty spot along the whole width of the six-yard box.

This was done to further map a goalkeeper’s traits: do they only command the space just in front of their goal or are they also willing to attempt interceptions further out in their box? And do they prefer to catch or punch in these different areas?

First, let’s look at both of the goalkeeping areas combined.

Overall Goalkeeping Area

Mark Gillespie had an impressive showing in our shot-stopping analysis, coming third in the league. His great stat performance continues as he tops the table for aerial command: of the average 7.7 high balls into the GK area per every 90 minutes (p90) he played, he intercepted 30.2% of them. Over 73% of those interceptions were caught balls, which was just above the league average. 

Dundee’s Swiss-Senegalese loan signing Seny Dieng was just below Gillespie in the rankings, intercepting 29.8% of the balls coming into his airspace.

Graph Whole Area.PNG

St.Mirren keeper Vaclav Hladky’s shot-stopping stats were noteworthy in that he made over a third of his saves with his feet, by far the most in the league. He is also the goalkeepers who choose to punch most often: he held only 52% of his interceptions but he did successfully come for the third most crosses in the league.

Hladky’s club colleague Craig Sampson was second worst in the shot-stopping category and there will be questions raise over his aerial command as well: he only intercepted 11% of the high crosses coming into his area.

There’s also significant difference between the two Hibs goalies: while Ofir Marciano’s shot-stopping stats were spectacular and Adam Bogdan’s far below average, the pattern is reversed when it comes to aerial command; Bogdan intercepted almost 8% more of the high crosses into his area.

It’s worth noting that Craig Gordon intercepted the second lowest of crosses in the league - added to his quite mediocre shot-stopping stats the data has not been kind to him during this review. When Gordon does come for the ball, he’s one of the best at holding on to it: 85% of his interceptions were caught, compared to the only 67% caught by his Celtic colleague Scott Bain.

Hearts’ Colin Doyle stood out in the shot-stopping stats by being the goalkeeper who held most of his saves and it’s the exact same story when it comes to crosses: he held a league-high 92% of all the high balls he intercepted. This man really enjoys catching a ball!

Table showing the % of high crosses intercepted successfully by the goalkeepers in each area.

Table showing the % of high crosses intercepted successfully by the goalkeepers in each area.

Inner and Outer GK Area

The six-yard-box, especially the part of it directly in front of the goal, is an area the goalkeepers are fully expected to control. Any high cross into this space can pose a grave danger to the defending team and a commanding presence by your goalkeeper is often needed to nullify such attacking threats.

So who is the king of their goalkeeping castle in the Premiership? It’s the man who likes to hold on to the ball: Colin Doyle. Almost 78% of the high balls that came into the middle of the six-yard-box were intercepted by the Heart’s goalkeeper. Not only that, he caught every single one of them. It’s a huge contrast to Hearts’ first choice goalkeeper for large parts of the season, Zdenek Zlamal – he only intercepted 40.5% of the high balls into the same area, just above half of what Doyle did, and he elected to punch a third of the time

Inner & Outer Graph.PNG

That places Zlamal second bottom in the league, with only Daniel Bachmann below him – and by quite the margin. The Austrian only claimed 29% of the crosses sent into this area. Bachmann seemed to choose his interceptions attempts carefully: he caught every single one of the balls he did reach.

For some goalkeepers there’s a notable difference when it comes to intercepting these high crosses in the inner and outer GK area. While Colin Doyle leads in claims in the inner area, he’s 15th when it comes to interceptions in the outer area.

It is just as pronounced when it comes to Craig Gordon: he is 6th for reaching high balls in the inner space, but he is bottom in the league when it comes to the outer area. Gordon’s shot-stopping stats – where he had the second lowest amount of ‘standing saves’ – hinted towards him relying more on diving to make saves rather than moving his feet to be in a better position when facing a shot (he also had the third lowest % of saves made with his feet). His aerial command data reinforces this view: he’s comfortable coming for high balls in his immediate vicinity, but a lot less likely to venture further out to claim a cross.

Craig Gordon crosses.png

For Daniel Bachmann it’s the opposite: he was last in claims within the inner GK area and 4th in the outer area – compared to Gordon we’re seeing two completely different types of attitudes to dealing with high balls into the area.

The three goalkeepers who had the highest rate of interceptions overall are very consistent when it comes to claiming high balls both closer and further away from the goal. Mark Gillespie tops the table when it comes to claims in the outer area but he’s a solid 7th in the inner area as well. Seny Dieng is even more consistent, ranking 3rd in the inner space and 2nd in the other, while Vaclav Hladky claims 5th and 3rd place in the two categories.

Table shows the % of high cross interceptions that the goalkeepers held, rather than punched.

Table shows the % of high cross interceptions that the goalkeepers held, rather than punched.

 

Conclusion:

Compared to shot-stopping stats, it’s slightly more difficult to pronounce a clear ‘winner’ in dealing with high crosses as there is simply more hidden and subjective information within the analysis, especially when it comes to how many times a goalkeeper came for the ball but didn’t reach it and the fact that staying on your line will at times be preferred to going for the ball. There’s also the speed and trajectory of the different crosses to consider.

What the data can tell us is which goalkeepers commanded their area the most, measured by how many of the high balls into their space they intercepted. For the 2018/19 Premiership season it was Motherwell’s Mark Gillespie. Together with placing 3rd in the shot-stopping stats, it is becoming clear that the Englishman had a very positive contribution to Motherwell’s upswing in results in the latter part of the season.

Gillespie crosses.png

Ofir Marciano’s shot-stopping stats were outstanding and by far the best in the league. For aerial command he drops dramatically to the 3rd lowest rate of interceptions. We can only be certain that this is fully representative of his strengths and weaknesses with a bigger sample over more than one season. It will be an interesting aspect to follow for the upcoming campaign.

Trevor Carson was bottom of the shot-stopping stats, but he does better when it comes to aerial command, rising to 10th. Gary Woods, third last in shot-stopping, only climbs to 14th in this category and it’s even more grim reading for Craig Samson: placing second last for saves, he intercepted the least high balls of all the goalkeepers in the league last season. With Vaclav Hladky 8th in shot stopping and 3rd in aerial command, there is simply no doubting that St. Mirren’s current number 1 had a significant better season than the man he replaced.

The last part of this season review will look at an area of goalkeeping that many managers are now putting as much importance on as shot-stopping and dealing with crosses: distribution.