Last week the Kitman Labs Performance Intelligence Research Initiative drilled down into data on the Premier League’s fixture congestion challenges, unearthing details on a new phenomenon we’re calling a congestion chain™ . This week we’re getting more specific after the Premier League again voted down a proposal to raise the number of substitutes to five (much to the ire of advocates like Liverpool’s Jürgen Klopp), and as issues of player welfare and club equality take even greater prominence. Hands may be tied on substitutions, but our analysis indicates clubs that boil down their complexity to get player rotation right at the individual athlete level — while taking advantage of the substitutions they do have — can keep talent healthy and let clubs emerge from this unprecedented period of congestion strong for the rest of the season. Because it doesn’t end in January.
The Most Dangerous Games
Just How Bad Are Injuries in 2020?
Evidence abounds of rising injuries in the Premier League, and the player welfare issue is real. To understand how much worse it’s been in 2020 – and what patterns might exist – we did a deeper dive using data from Premier Injuries for a more complete picture. We found that injuries are higher in 2020, though perhaps not as high as expected – except within certain defined periods in which we see injuries spiking earlier relative to last year.
Injury rates spiked early. By day 5, Premier League teams were seeing a 25% increase compared to last season. By day 10, teams had 100% more injuries.
As well, injuries jumped between Days 5 and 15 of the season, which makes sense given higher fixture congestion due to the overlap of the Premier League with the EFL Cup. Similarly, between Days 30 and 45, injuries climbed to a level 20% higher than the same period last season. We assess this is due to congestion between the Premier League, Champions League and the international window.
Looking Through the Lens of the Big Six
Surprisingly, the “Big Six” (Arsenal, Chelsea, Liverpool, Manchester City, Manchester United, and Tottenham) are getting injured less this year, even though they face higher degrees of congestion. On average, the Big Six have 3.2% more availability year, the rest of the League have 4.4% less availability at a player level. This seemed counterintuitive at first: if Big Six clubs face more congestion chains why are they seemingly healthier, or given the relatively small change, not any more more injured than they were in prior seasons and no more injured than the rest of the league?
Are Rotations Keeping Teams Healthier?
Limited by substitutions, teams appear to be employing player rotation to a greater degree: following Day 10, when injuries spiked by 100% relative to last season, rotation catapulted to 200% and reached 300% by Day 20.
Digging back into The Big Six view, they have switched their starting lineups 28% more than the rest of the league this year. They’re also using an 11% larger pool of players.
The exceptions are Manchester City and Liverpool, who have experienced 56% more player games missed and 69% more player games missed respectively. This is coupled with the fact that they’ve had amongst the least amount of rotation of the top six.
The Playing Field Is Not Level, Even in the Big Six
Some are in the Champions League. Some in the lower-tier Europa League. In the latter, Arsenal and Spurs have the ability to rotate out a large portion of their squad. But Man City, Chelsea, Liverpool, and Man United don’t get a similar break. They simply can’t rotate large portions of their starting line up in the Champions League and expect to maintain performance. For them, getting rotation right is key.
With Liverpool and Manchester City, rotating fewer players than most of the The Big Six, but still very likely to maintain consistently high performance levels, we asked the following question: “Given the association of lower injury rates and rotation, how can teams effectively manage player minutes while still achieving the highest levels of performance, not only for the Christmas period, but for the remainder of the season?”
So how can teams navigate this? Rotation, Rotation, Rotation.
While teams can’t control the fixtures and five substitutions have been voted down again, the data shows rotation is associated with lower injury rates. This means teams can break the congestion chains at an individual player level.
Despite the challenges, smart teams can still get an edge if they think about this on the granular level, on a congestion chains per player basis. It’s not easy to manage minutes and maintain performance. It requires meticulous data-driven planning that considers the length of the congestion chains, player synergies, tactics, opposition analysis and player availability. Data makes it achievable to tackle this complexity.
Recommendations for surviving Christmas and Beyond
- Meticulously analyze and manage minutes to preserve what is needed for individuals to perform and group cohesion to be maintained, while also delivering fresh athletes across these periods and leave an intact squad for the season’s back half.
- Evaluate congestion chains to determine the specific levels of rotation and substitution needed for varying lengths of chains.
- Ensure effective rotation and substitution by analyzing and understanding the right amount of stimulus needed to perform for a team’s unique style of play, and providing all players with the right level of training to prepare players for the demands of the game.
It’s important to note that teams doing well from a health perspective will need to know why that’s the case if they’re to maintain it through the Christmas crush. For them, this likely means keeping their current levels of rotation. But for others, getting healthy might require a 2-3x increase in rotation, which could have potentially drastic effects on team’s on-pitch congruence, chemistry and performance.
The strategy and execution of managing these competing priorities falls into the realm and responsibility of coaches and managers. But with substitutions seemingly fixed for good for the rest of the season, rotation is the key to maintaining performance and keeping athletes healthy during the most wonderful – and injury-ridden – time of the year.
I welcome your feedback in the comments below, on my Twitter account or at email@example.com.
This research was provided by the Kitman Labs Performance Intelligence Research Initiative and authored by Ray Hamill, Derek McHugh, PhD, and Martin Buchheit, PhD. This analysis included all games between the start of the Premier League season and the end of the 9th matchday across the past three seasons.
All injury data is from Premier Injuries.