Injuries, Rotation and the Value of Subs

How much has squad depth contributed to success or failure in the Premier League?

In an attempt to break out of the doom spiral of following Liverpool in 2025/26, I opened a thread where anyone could ask football questions which I would attempt to answer (here, feel free to add to it). This query, from Butty, is essentially a three-parter:

“I’d be interested to understand how much squad depth contributes across the league. E.g. how many results were positively changed by substitutes or deputies. Maybe even going further, looking into if rotation reduces injuries or significantly improves performances of key players compared to previous seasons.”

Quantifying the impact of any of this is not easy. There are, however, some pertinent numbers for Liverpool which tell a tale about the problems they have had to endure this season.

We’ll begin with injuries. Leaving aside the construction of the squad, fitness issues ultimately shape what a manager can realistically change from week-to-week or in-game.

Arne Slot delivered a positive impact in this regard last season (as you can read in detail via the link below). Premier Injuries measure time-loss injuries, which are “any injury that results in a player missing at least one competitive fixture”. Liverpool suffered 4.3 per 1,000 minutes played in 2024/25 after being at 6.7 in Jürgen Klopp’s final campaign.

Arne Slot proved Availability is the best Ability

This improvement combined with Arsenal and Manchester City seeing their figures rise to 6.9 and 6.5 respectively last term likely helped the Reds win their second league title in six years.

Liverpool are at 7.9 this season.

That’s my calculation; it may be different with Premier Injuries, who provide their figures in an end of season summary rather than throughout the campaign. Their number shouldn’t be wildly different, with the Reds having collected (by my count) 34 time-loss injuries across 48 matches (4,320 minutes).

Despite losing players more frequently from what most would consider a weaker squad, Slot has been making fewer changes to his starting XI.

Rotation is not easy to assess across the Premier League, as clubs with European commitments play far more often. Manchester United will contest 40 games in 2025/26 whereas Liverpool will finish with somewhere between 57 and 60 on their ledger. Probably 57.

Managers also frequently make more changes for domestic cup games, especially if facing lower league opposition. The fairest method for comparing clubs is to look at the number of line-up amendments they make from one league game to the next.

The figures for Liverpool are a touch misleading. Slot averaged 1.9 changes per league match before the title was won last term, then raised that figure by giving some of his lesser lights a run-out.

Either way, these numbers suggest that rotation alone has no correlation with success. Brentford have improved after making the joint-third most changes per game; Newcastle and Wolves are lower in the table despite making even more. Nottingham Forest have maintained the most stable line-up in 2025/26 despite having four ‘permanent’ managers who could collectively be responsible for relegation.

While Slot is making essentially as many line-up changes between league games this season as he did in his rookie year, the numbers have shifted more notably for substitutes. That’s true for the volume of them, their average time on the pitch and the tangible output they have delivered in goals or assists.

When comparing Premier League managers, the analysis has to start in 2022/23. This was the first full season in which teams were permitted to make five substitutions. It also makes for an interesting time frame for analysing Liverpool, as both of their managers in this period had a poor season and a title challenging/winning one.

A remarkable coincidence occurred in Slot’s first campaign. His rates for subs per game (4.34) and the minutes they averaged (19.7) were identical to Klopp’s across his final two seasons. It’s why the Dutchman’s 2024/25 dot is not visible on this chart.

Slot’s numbers have dipped to 3.97 and 19.1 respectively this term, both of which are below league average. You can also see from the size of his 2025/26 marker that goal contributions off the bench have not been overly forthcoming.

The Reds’ squad is unquestionably weaker this term. This is highlighted by Slot’s goal scoring substitutes in the 2024/25 Premier League being Diogo Jota (with three goals), Darwin Núñez (two), Trent Alexander-Arnold and Luis Diáz (one apiece), none of whom remain at the club. The majority of the nine sub assists from last season have also disappeared from the squad, albeit Curtis Jones (two), Conor Bradley and Alexis Mac Allister (both one) remain.

Even with Mohamed Salah delivering a season for the ages, contributions by the bench were still important last term. Jota scored equalisers against Fulham and Forest. Goals from Darwin and Trent earned road wins at Brentford and Leicester respectively. It took less than six minutes after his introduction for Jones’ to assist Salah for the Anfield winner against Brighton. Here are eight additional points that kept the title train on track.

Slot’s changes early in 2025/26 were having an impact too. The decisive goals in the first two league games came from the bench, with Federico Chiesa adding to his strike against Bournemouth with one at Crystal Palace that should have been worth a point. He also assisted an equaliser against Manchester United in another game that should not have been lost.

This well has been dry since Christmas. Alexander Isak’s opener at Tottenham on December 20 was the last Premier League goal contribution by a Liverpool substitute. The others this season, for the record, were assists from Salah and Wataru Endō for goals in matches that the Reds were already leading.

The total of four Premier League goals by subs puts Liverpool joint-14th in the division. Tripling their total would only put them one ahead of Arsenal, with Fulham (10), Aston Villa and Brighton (both nine) also over twice as productive.

The situation could be worse, the bench less impactful. The only goal a Manchester City substitute has scored saw Rayan Cherki put them 4-0 up at Wolves on the opening weekend. It was academic.

And although Liverpool haven’t had many goals by subs this season, no team has taken the lead thanks to a non-starter scoring on more occasions.

The Reds are the only team to have completed the set of the three types of this contribution. Chiesa’s goal against Bournemouth proved decisive - Salah added to it in stoppage time - then Rio Ngumoha struck a winner at Newcastle the following week. Isak’s effort in north London put Liverpool 1-0 up in a match they would later win 2-1, so as important as it was, it did not determine the outcome of the game.

Slot hasn’t summoned too many goal contributions from his Reds bench but they have tended to be impactful. Harvey Elliott’s goal to secure a win in Paris has been the most important of the 12 strikes by substitutes in cup competitions, for instance.

At worst, the Liverpool head coach appears to have the ability to make positive changes from the bench if he has quality options available. The make up of the squad and the injuries they have suffered are counting against Slot this season though.