Premier Injuries Head of Content Jason McKenna is back with another piece on how understanding injury data can help us understand team tactics
Arsenal’s Secret Load Management?
When we consider football tactics we often see them through the lens of targeting immediate sporting success. A tweak in personnel or formation is due to wanting to win the upcoming match. But this season we may be seeing in-game tactics being used for longer term goals: so that players can “peak” at the right time of the season.
This is not a new approach, but it is fairly new to the Premier League, and Arsenal’s rampant form since the Winter Break is an excellent insight into what may be a future way that all teams try to periodize their seasons. Instead of focusing on just training for load management, the Gunners have also seemingly used their tactics in order to increase the longevity of their players through the season and so increase their chances of winning the title at the end of the campaign.
More than just being proactive with player management, we may instead see teams planning for a whole season’s success through a style of play.
Why this approach for the Gunners?
The ill-fated 2022/23 title race will have shaped the preparations this season. Arsenal started that season in excellent form and seemed to build an almost unmatchable lead at the top of the table. But the campaign fell apart when injuries and poor performances mixed and the side started dropping points. This pre-emptive early peak was clear: Arsenal earned 2.64 points per 90 before the Winter World Cup, but won only 1.96 points per 90 after.
So, seemingly, a new approach has been deployed in the 2023/24 campaign. Arsenal have focused on lowering their risk and timing their players to peak at the optimal time of the season.
I wrote previously for Analytics FC that the start of each season is when there is an increase in injuries. During this time period we actually see some of the highest injuries per 1k mins played showing that it is a time where squads have to be careful to get results whilst also not affecting their squad for the season.
Adding to this, the Christmas period for each season is where the schedule is the most hectic; then we go into a Winter Break. It is therefore important for players to be managed during these times of high exposure and high likelihood of injury so that they are available into the late stages of the season when titles are won and trophy runs are decided. But this also means that you need to be able to make sure that the players are not too exhausted from the campaign.
So Arsenal instead appear to have tailored everything to peak in the New Year, specifically after the Winter Break. This season the team has started slowly and the team were able to get over this hump period relatively unscathed, keeping their players fit and also managed to pick up the necessary points that have kept them in the title race.
What Is Player Peaking?
Birmingham University analysis has found that “often athletes peak too early rather than too late”. It is not an exact science as it is hard to account for all the variables, but timing peaks for certain stages of seasons or for specific competitions is something that athletes have been trying to perfect for years. Dr Jamie Pringle of Birmingham University has described how difficult it is to manage a single athletes “peak”, let alone a whole squad, to make sure that they are reaching as near as possible to their athletic output during the most crucial part of the season. Dr Pringle has said that there are issues around the fact that there is “relatively sparse published research” and that there is a multitude of factors as “it’s the science of muscle fatigue; it’s the science of adaptation, of strength, power, and endurance development; and just as importantly, it’s the science of how those hard-earned gains are maintained”.
An optimised training schedule built around competition must be created, so that players can maximise their physical and psychological output at the correct time of the season. Previously these schedules were created in macrocycles, meso-cycles and micro-cycles with periodised training models used to target preseason, midseason, latter stages of the season, postseason and offseason stages of the campaign (as seen below). These plans were created but the details were missing due to a lack of data and AI to help decision making. Now, with the advanced data analytics departments used at clubs squads can run specific schedules, but players can also be given individualised schemes that fit their own physical limitations.
In the traditional methodology, volume was ramped up during preseason to create base levels of fitness through the season and it was not ramped down until after the first half of the season had started. But the new scheme introduced by Arsenal, targeting that initial spike of injuries at the start of a season, is seeing volume decreased earlier and saving the ramping up for in the second half of the season after the Winter Break.
Why at this point of the season?
As discussed elsewhere, Arsenal peaked too early last season. But this may have been in a bid to offset the risks of the Winter World Cup, which indeed did rob them of Gabriel Jesus. Teams have to work with managing risks and last season before the World Cup was when managers had the most control over their players, whereas after there were unknown variables of how players would return to squads. Unfortunately the gamble did not pay off.
With this season the campaign is much more predictable and easily to plan around. The timing of the Winter Break is perfectly situated in the schedule. It is short enough to allow players to recuperate but not decondition. It has been found that endurance athletes can rest and recuperate for short amounts of time (1-2 weeks) without experiencing losses in their abilities. This has led to the conclusion from Cullinane et al. that “competitive athletes should consider brief periods of exercise cessation” for recovery, treat minor injuries, and therefore lead to a better longer term output.
Tal Brown of Zone7 has discussed how players, and teams, can be controlled when they will peak. This belief has therefore been coupled with the timing of Arsenal’s winter break. The AI-based methodology of Zone7 is seen as a way to improve team decisions working as an “autopilot” assistance to medical staff. It does not take away decisions from club hierarchy: personal, context-based choices are still up to the manager and those around him. However, this system is able to flag specific markers that may mean a player is being overworked and in need of rest. Brown has also discussed that teams can increase output of players “like a dial” and that the “dial” can be turned up or down so that certain areas of the season can be targeted. Due to the extensive data sets that are now available to teams this sort of targeted output in training and in games is much easier to manage as Biomarkers are used to evaluate players fitness. Medical staff can now evaluate the metabolic, mechanical, and oxidative stresses that players are under and can then make suggestions if rotation or rest is needed.
The Evidence From This Season
The inner workings at Arsenal are a secret, but Zone7 have already had success under their belts with working with Liverpool in their quadruple chasing season of 2021/22. Newcastle United are another team that uses an external AI company, ORRECO. It would be no surprise if the Gunners have seen this success and replicated it, as this sort of marginal gain is so important when competing with the near perfect teams of Liverpool and Manchester City.
But the numbers also speak for themselves looking from the outside in. It is clear to see comparing the first half of the 2023/24 campaign to the the post-Winter Break performances that a periodisation has happened with Arsenal, but with the unique quirk of it involving tactical changes rather than just player load management in the more traditional way.
Tactically it has been widely noted that Arsenal were conservative at the start of this season compared to how open and expansive they were in the pre-World Cup period in the 2022/23 season. The style of football, at times, was criticised as it was very defensive, which was especially showcased by four 1-0 victories on the road by Gameweek 13.
This is also seen in the data where the team was much more reserved before the Winter Break (Gameweeks 1-20). The data is more limited in the post Winter Break as it is only 7 (Gameweeks 21-26) but even from the playstyle it is clear to see that Arsenal are much different team to start the season. The team are much more vertical in their play with more Key Passes and Through Balls being played per 90, and this has allowed the attackers more opportunities in the box. Adding to this the team are creating more Big Chances and this has accumulated in 1xG per 90 increase.
The reason for this may best be showcased through the PPDA data. A 17% different in the pressing is more conservative and it shows that Mikel Arteta at the start of his team wanted to make sure that his team were managing their exposure.
| Metrics (All per 90) | 2023/24 Before Winter Break | 2023/24 After Winter Break |
| Expected Goals (xG) | 1.88 | 2.88 |
| Goals Scored | 1.85 | 4.17 |
| Shots in the Box | 11.40 | 13.50 |
| Key Passes | 12.30 | 14.83 |
| Areas of Chance Creativity | 48% Central | 58% Central |
| Big Chances Created | 1.95 | 3.17 |
| Final 3rd Passes | 192.65 | 199.50 |
| Through Balls | 1.50 | 1.57 |
| Arsenal PPDA | 9.10 | 8.94 |
| xG Conceded | 0.8 | 0.3 |
Conclusion
One can see that from the tactics and the data that Arsenal have switched from a more conservative style of their play to a much more aggressive attacking way. This is because of the “dialing up” abilities that Tal Brown has described that AI, or general, data-based decisions, allow.
The team deployed a conservative style at the beginning to navigate the high injury incidence periods, get results and then make sure that players could then begin to peak after a rest during the Winter Break. All these calculations have led them to believe that allowing their players to peak from now until the end of the season will give them the best chance at silverware this season.
Liverpool used similar methodology in the 2021/22 season helped by the work of Zone7 and if Arsenal are successful too, this method of coupling load management with tactics may become a new approach to club management.
Header image copyright IMAGO / Sportimage
