In a rule change that Unai Emery could have only dreamed about during this reign at Arsenal, teams are now allowed to make up to five substitutions during the remaining fixtures. Luckily, in order to prevent time wasting with these introductions, each team will only have three opportunities to make changes throughout the match with an additional opportunity at half time. But who is likely to embrace this new tactical weapon in the Premier League?
You might expect the teams higher up the league table with the deeper squads to embrace this new rule but usage in the Bundesliga since its return may suggest otherwise. Bottom placed SC Paderborn 07 have used all five of their substitutions in every game so far, whereas only Wolfsburg have used fewer substitutions (20) than reigning champions Bayern München (23), who are averaging 3.8 changes per game. In fact, the moderately strong correlation between league position and substitutions (0.6), suggests that teams lower down the table are more likely to make more substitutions.
While substitution usage has varied between Bundesliga teams, the short preparation time they have had to regain match fitness has seen all of them make the most of their squads. Each team used between 19 and 22 different players in their first five games in the new world, nearly 1.5 more players more than they averaged during their first five match days of the season. It appears that the stronger teams may be exploiting their squad depths by rotating their starting eleven between match days but maintaining continuity during the game.
But will we see the same patterns emerging when the Premier League resumes? Managerial changes have certainly had an influence, but it is also reflective of quality in depth that three of the ‘Big Six’ appear in the top five for the number of different players used so far this season, each using enough players to make up two and a half starting elevens each.
At the other end of spectrum, the consistent squads of teams like Wolves and Leicester have been key to their successes in recent seasons, with Leicester using even few players so far this season (21) than they did in their extraordinary title winning season (23). Manchester City make a surprising appearance in the bottom five, using only 22 players in their 28 games so far. While their squad is packed with talent, Pep Guardiola appears to keep faith in a smaller group of players than most of his rivals.
Meanwhile, Liverpool’s Jürgen Klopp and Brighton’s Graham Potter have been the current managers to most frequently turn to their bench for fresh legs, both failing to use their full three substitution allowance in only two games each this season. Much to the delight (or not) of Liverpool fans, Jürgen Klopp has turned to fan favourite Divock Origi 17 times, with only Manchester United’s Mason Greenwood making more substitute appearances this season (18).
As well as appearing in the bottom three teams for unique player usage, Burnley’s Sean Dyche also keeps faith in his starting line up more often than any other manager, making exactly two substitutions per game over the season so far. Burnley’s consistency this season has led them to within one point of the much coveted 40-point survival marker.
While the numbers above give us a basic overview of squad usage, we can take a closer look at the distribution of minutes given to the players within each team. Squad usage over a single season can be influenced by external factors, such as player availability or managerial changes, but we can use Team Line up Entropy (TLE) to estimate a team’s reliance on a core group of players. TLE is a metric which attempts to describe team-level variation in playing time distribution: teams whose minutes are played by a small number of players have low entropy, whilst those who split the available minutes between many players have high entropy.
If we normalise the TLE values on a scale where zero represents the same ten outfielders playing all of the minutes over the season, and one represents a typical Premier League squad size of twenty five players sharing the minutes equally, we can pull out some interesting insights.
Sheffield United and Wolves are the two teams most reliant on their core group. Both teams were similarly reliant in their respective final seasons in the Championship, but their squad depths may be tested with a congested schedule combining with an unusual lack of preparation time to regain match fitness.
Despite regularly using their maximum substitution allowance, Liverpool’s minutes are actually played by a smaller group of players than all of their ‘Big Six’ rivals. However, given the inevitability of their title success, we may see them to continue to max out their allowance and give more time on the pitch to their impressive fringe players such as Naby Keïta and Takumi Minamino.
Given the uniqueness of this rule change and its debut in competitive fixtures, it is difficult to predict how teams will seek to use it to their advantage. Professional football matches are won by small margins and so there could well be tacticians and analytical departments around the country trying to squeeze any marginal gains they can out of this new tactical flexibility.
What seems most likely is that the teams with the greatest quality in depth will be able to rotate their starting line ups during an inevitably congested schedule without needing to disrupt the balance of players during the game itself. It is most likely to be the managers lower down the table who will be the ones looking for inspiration from their socially distanced dugouts.
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