Are injuries really to blame for Liverpool’s drop-off in points this season?

With 33 fewer points than they had after 25 league matches last season, it is an undisputable fact that Liverpool has experienced a significant drop-off in form in the Premier League this year. One reason often used to explain this disparity is the impact of injuries on the Liverpool squad. The Reds lost talisman Virgil van Dijk to a season-ending ruptured cruciate ligament in Gameweek 5, while his centre-back partner Joe Gomez endured a season-ending patella injury between Gameweeks 9 and 10 whilst on international duty. Yet the Premier League champions have also suffered long-term injuries to other players in their squad, including Thiago Alcantara, Joel Matip, Diogo Jota and Kostas Tsimikas.

However, whether injuries alone can explain Liverpool’s drop-off in form is open for debate. Many argue that injuries are “part and parcel” of any season, thus, Liverpool are not in a unique situation. Manchester City being without Aymeric Laporte, Kevin de Bruyne and Sergio Aguero, for example, is often used as the counter. So, I’ve set out to see whether there is evidence to support or disprove the narrative that Liverpool’s drop-off is principally due to their injury problems. Though this blog piece is unlikely to provide a definitive answer – it will always be a subjective opinion – I hope it will delve deeper into the issue than other articles have been able to.

It will be a two-part series; the first (this one) will consist of a direct comparison of Liverpool this season to last season to measure the impact of injuries on their squad; the second will be more of a comparison of Liverpool’s situation this season to another team’s, like Manchester City, to determine whether Liverpool’s situation is unique or not.

HOW TO MEASURE THE IMPACT OF INJURIES ON A SQUAD

Most analyses into Liverpool’s injury crisis have been quite superficial, focusing on minutes played or average number of players injured per game. While these measures are still important and helpful, to really investigate and understand the impact of injuries on a squad, we need to go deeper.

It is true that all teams have injuries to deal with across a season. However, an injury to a player that typically spends 75% of the season on the bench is far different to an injury to a player that plays 60+ minutes in 75% of the team’s games across a season. Therefore, to understand the impact of an injury, we need to understand the importance of each player to their team. Being able to quantify a player’s importance is crucial to then measure and compare season-to-season or team-to-team.

For me, there are two important factors to consider: (1) availability; and (2) utility.

Availability refers to how available a player is for selection. It can be worked out by taking the total possible minutes a player could play compared to the total possible minutes in a season and then converting it into an availability score. This is where injuries become important. If a player is sidelined for four matches, it means their availability score will decrease. Yet, injuries are not the only reason why a player may not be available, it could be due to suspension, personal reasons or a youth player playing for one of the youth teams. However, as injuries are the principal focus of this piece, all other reasons will be counted under “other” and kept separate from the analysis.

Utility, on the other hand, refers to how often a player is used when available for selection. It can be worked out by taking the total number of minutes played compared to the total available minutes the player could play and then converting it into a utility score. This helps separate bench players from the starters. For example, if you have 100% availability, but only play 25% of minutes, your utility score will be lower than a player who may only be available 75% of the time, but plays 75% of minutes when they are.

Therefore, the equation for working out a player’s importance to a team is:

IMPORTANCE = AVAILABILITY X UTILITY

APPLYING THIS METHOD TO A TEAM

This method is easily applicable to all teams and could be used to measure all sorts of aspects, such as injuries, suspensions, or varying importance of players. Central to its success though, is how it conceptualises a team. Each team has a score of 11, reflecting the eleven players needed on a pitch to play football. How each team makes up their score of 11 will be different though, depending on the formation they use. For example, most teams now play a 4-3-3. This splits the score into four parts, which make up the value of 11:

  • The goalkeeper counts for 1
  • The defence counts for 4 – 1 for LB, 1 for RB, and 2 for CB
  • The midfield counts for 3
  • The forwards count for 3

In a 4-4-2 formation, this would be slightly different. The defence would still count for 4, but the midfield would also count for 4, while the forwards count for 2.

In a 5-3-2 formation, again, this would be different. The defence would count for 5 – 1 for LB, 1 for RB, and 3 for CB – while the midfield counts for 3 and the forwards count for 2. This allows a team’s formation to be taken into consideration.

Under Jurgen Klopp, Liverpool most consistently play a 4-3-3, so that will be the formation used in this analysis.

ANALYSING LIVERPOOL

Below is a gantt chart showing Liverpool players’ minutes for the 2019-20 Premier League season:

Dark red blocks represent missing the match because of an injury; light red blocks represent missing the match for another reason (suspension, personal reason, or rest); yellow blocks represent being an unused substitute; and grey blocks represent a player playing for a different club or youth team. Any minutes played by a player are quantified inside a green block.

Below is a gantt chart showcasing the same data but for the 2020-21 Premier League season (up to first 25 matches):

This data was then collated and converted into further tables. Below is a table comparing Liverpool players’ importance last season vs. this season. It includes each player’s availability score, utility score and overall importance/involvement score.

What it shows is that ten players have decreased in importance/involvement from the 2019-20 Premier League season to the 2020-21 one. Three of the ten have moved to different clubs: Dejan Lovren (Zenit St. Petersburg), Adam Lallana (Brighton & Hove Albion) and Harvey Elliott (Blackburn Rovers – loan). Of the remaining seven, three are “nailed-on starters” – Trent Alexander-Arnold, Virgil van Dijk and Joe Gomez – while four are “bench players” – Adrian, Naby Keita, Alex Oxlade-Chamberlain and Divock Origi. While the declines vary in severity, the biggest drops are seen in van Dijk (-0.835), Oxlade-Chamberlain (-0.353) and Gomez (-0.322).

On the flip side, twenty players have increased their importance/involvement from last season. Though the reasons may vary, the most obvious ones are new arrivals – Thiago (+0.403) and Diogo Jota (+0.223) – and players stepping up in others’ absences – Nathanial Phillips (+0.246) and Curtis Jones (+0.385).

This is shown more clearly when putting Liverpool players’ importance/involvement scores for both 2019-20 and 2020-21 Premier League seasons in graph form:

And the differences between their scores for both seasons:

However, this table does not tell us whether the decline or increases are due to injuries. Thus, below is a table showing Liverpool’s injury burden last season vs. this season. It includes a player’s overall unavailability score, and then breaks it down into two further scores: (1) injured score; and (2) other score.

What this table shows us, then, is that Liverpool’s injury burden increased significantly from the 2019-20 season to 2020-21. Last season, they had an injured score of 2.921. This season, their injured score doubled to 5.880 (+2.959). While we cannot argue that this is the worst score this season – or ever – as I have not analysed each team yet, it is clear that Liverpool definitely have had a more severe injury problem than they did last season.

Again, this can be shown more clearly by converting Liverpool players’ injured scores for both the 2019-20 and 2020-21 Premier League seasons into graph form:

In fact, Liverpool have eight players with scores over 0.400, which means they have missed 40+% of this season already (8+ Premier League matches). These players are: Virgil van Dijk (+0.800), Joe Gomez (+0.680), Naby Keita (+0.600), Joel Matip (+0.560), Diogo Jota (+0.560), Kostas Tsimikas (+0.520), Thiago (+0.480) and Alex Oxlade-Chamberlain (+0.440). In comparison, Liverpool only had two players last season with scores over 0.400: Joel Matip (+0.526) and Xherdan Shaqiri (+0.526). Though it must be noted that last season’s scores are calculated based on a full 38-game season, whereas this season’s scores have been calculated based on 25 matches.

Yet looking at the difference in the players’ scores from 2019-20 season to 2020-21 paints an even worse picture (this has been shown in the graph below). Whereas Matip’s difference is low (+0.034) because he has had lengthy injury spells in both seasons, the staggering differences for van Dijk (+0.800) and Gomez (+0.680) show just how much Liverpool have suffered at the back. To lose your two main centre backs to season-ending injuries within the first 10 games of the season would be devastating for any team. To showcase just how much this has impacted Liverpool’s season, I’m going to delve deeper into the make-up of Liverpool’s starting XI.

COMPARING LIVERPOOL’S STARTING XI

Below are four tables, showcasing the make-up of Liverpool’s starting XI from the 2019-20 Premier League season to 2020-21:

What the tables show most starkly is the drop-off in defensive output from Liverpool’s defenders. During the 2019-20 season, their defenders had an importance/involvement score of 3.923, with the remaining part made up of James Milner filling in at full-back in the absence of either Andy Robertson or Trent-Alexander-Arnold. During the 2020-21 season so far, despite having three more defenders, the defence’s importance/involvement score dropped to 2.805. This does not reflect Liverpool changing formation to a 3-4-3, but rather the fact that Fabinho and Jordan Henderson have had to step in consistently at centre-back in the absence of Virgil van Dijk, Joe Gomez and Joel Matip.

When you account for this fact and include Fabinho’s, Jordan Henderson’s and James Milner’s minutes played in defence (shown in the tables below), it shows how much the midfield has had to fill in for the defence’s injury problems. In fact, 80.7% of Fabinho’s involvement this season has been at centre back, whilst it stands at 38.7% for Henderson. However, this still has the knock-on effect of taking away two of Liverpool’s most involved midfielders from their preferred positions. Fabinho’s involvement in midfield is down 77.9% on the previous season, while Henderson’s has decreased by 29.1%.

Here is the above table in graph form:

And who has stepped in to fill the void in midfield? Newcomer Thiago and academy product Curtis Jones mostly. On the face of things that might not seem like a problem, but that is a lot of responsibility to place on a new arrival – even if he has won countless prestigious trophies – and a 20-year-old, especially given the importance of the midfield for successfully maintaining the press in Klopp’s system. Midfielders under Klopp must be quick, dynamic and willing to run. Jones does fit that profile and has delivered great performances this season, but he is still largely inexperienced and inconsistent. Alternatively, Thiago does not typically fit the mould of a Klopp midfielder. He was brought in to unlock low block defences through his bold range of passing. Relying on him to run and fill the void of the likes of Fabinho and Henderson appears misplaced. Thus, finding a solution that would maximise the midfielders Liverpool do have available seems like the more sensible tactic moving forward.

CONCLUSION

When delving deeper into this Liverpool team, it becomes clear why they have struggled to hit the heights they did last season. Injuries seem most certainly the biggest factor for this, with Liverpool’s injured score doubling to a worrying 5.880. Given my next piece in the series will compare Liverpool’s 2020-21 season to another team’s, it should become apparent whether this score is in the freakish realms or just another injury-hit season. For now though, the argument that Liverpool’s season has been derailed because of injuries appears to stand strong.

The defence, in particular, has taken a battering. The loss of talisman Virgil van Dijk could not be more damaging. Liverpool not only lost a player who was 100% available last season, but who played 100% of the minutes possible in the Premier League. To have that sort of importance/involvement on a team (i.e. a perfect score) is rare. So to lose a player like that, five games into the season, was always going to be a tough ask to rally against. This was then further compounded by the loss of Joe Gomez, and the recurring injury problems of Joel Matip. Though the defence has tried to step up in their absence, the majority of defensive output was left to Fabinho and Jordan Henderson to make up, at the expense of their output in midfield. This then left Thiago and Curtis Jones to fill in their voids in midfield. An analogy of dominoes falling one by one in quick succession seems a fitting way to explain the first 25 matches of Liverpool’s 2020-21 Premier League season.

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