Alisson vs Kelleher: What do the Numbers Really Tell Us? – Analysis | OneFootball

Crunching the Numbers: Arne Slot’s Goalkeeping Decision

The past few weeks have been quite awkward for Liverpool’s new head coach, Arne Slot. With key injuries to the likes of Alisson Becker and Diogo Jota, the Dutchman has still managed to guide the Reds eight points clear at the top of the table.

In the absence of Alisson, Caoimhin Kelleher has proven his worth once again with a run of really impressive performances across the opening 12 Premier League games of the season. Some have suggested that the Dutchman faces a huge decision upon the imminent return of the Brazilian, which we’re going to take a closer look at today…

Conveniently, both goalkeepers have now played six Premier League games each, so we’re going to crunch the numbers and get to the bottom of this debate.

Surface Numbers – Shot Stopping

Now, the most obvious way to determine a goalkeeper’s ability is based on the amount of goals they’re conceding. Kelleher has conceded six goals across his six Premier League games this season, whereas Alisson had let in just two in the same number of games. However, of course there’s a lot more to it than such an easy statistic.

There’s also the argument that Kelleher has faced tougher opponents, facing the likes of Arsenal, Chelsea and Brighton in the Premier League. The Irishman has made more saves (16) than Alisson (15), but the Brazilian boasts a save percentage rate of 88.2% compared to Kelleher’s 73.9%.

Photo: IMAGO

Staying on the subject of shot-stopping, we can next look at their performance on post-shot expected goals against. Alisson’s PSxG stands at 4.5, despite conceding just two goals, with an over-performance of 2.5 – which is simply sensational. Now, Kelleher’s numbers are nothing to frown at either, with a PSxG of 6.9 and an over-performance of 0.9.

I also suspect that yesterday’s poor defensive display against Southampton may have swayed these numbers slightly. In that game, Kelleher also produced a penalty save to again showcase his elite ability in that department, despite the Saints scoring the rebound.

Passing/Playing Out From the Back

This topic has divided Liverpool fans pretty heavily. I spoke to former Liverpool midfielder Jermaine Pennant last month, who suggested that the Reds were severely missing Alisson’s ability on the ball, to which many disagreed. Therefore, I’m really curious to see how these numbers line up.

The first thing you notice from the numbers, is that Kelleher is far more likely to go long with 67 attempted ‘launch passes’, compared to Alisson’s 40. In terms of completion rate in that area, Kelleher tips the Brazilian by just 0.9%.

Photo: IMAGO

This difference can be seen further from the keeper’s goal-kick stats. 66.7% of Kelleher’s goal-kicks go long (further than 40 yards), whilst just 23.1% of Alisson’s hit that threshold.

Moving away from goal-kicks, the average length of Kelleher’s passes is 29.6 yards, compared to Alisson’s 24.9. This can often help the side in transition though, by getting the ball up to the danger men quicker, which was a common aspect in the win over Aston Villa.

Other Stats

Just to cover all bases, I took a look at both keeper’s ability on crosses. Kelleher has faced a huge 68 crosses across his six appearances, with a stop percentage of 4.4%. There wasn’t much in this one at all, with Alisson facing significantly less in terms of volume of crosses with 48, but a similar stop percentage of 4.2%.

Photo: IMAGO

Finally, there was their ability as a sweeper-keeper, which Alisson has pretty much nailed over recent seasons. The numbers backed this up with the Brazilian performing more defensive actions outside of the box (10-7) and with a much higher rate (1.70-1.17).

Looking Ahead

As expected, Alisson is still performing to a higher level than Kelleher in most departments, which is of course expected. It’s also important to stress that this is in no way to discredit Kelleher of his brilliant performances in Alisson’s absence, he has still been one of Liverpool’s standout performers over the last six games.

However, despite his injury struggles, Liverpool still own the best goalkeeper in the world and will still play a pivotal role in the Reds’ title challenge. It’s an absolute joy to have two of the top goalkeepers in the world at the moment, which I truly do think is the case. As for Kelleher, whether his future is at Liverpool or elsewhere, whoever gets a hold of him has a serious player on their hands.