Clubs run extensive physical testing at the start of each season and build expectations from the results. The predictive value of those tests is considerably lower than the effort invested suggests.
The testing conditions are unrepresentative
Pre-season tests are conducted rested, on a controlled surface, without accumulated match load or travel. Those conditions never occur again during the season.
A measurement taken in that state describes a capacity ceiling rather than what a player will express in a competitive fixture in February.
Tests that are highly reproducible in the laboratory can therefore correspond weakly to what happens on a matchday.
Fitness qualities move quickly once matches start
Aerobic capacity and repeated-sprint ability respond to training within weeks, so a July figure ages rapidly. Players arriving from different summer schedules also converge as the season progresses.
Ranking a squad in July therefore captures where players were in their individual preparation rather than where they will be.
Clubs that repeat testing during the season get considerably more from the exercise, though fixture density limits how often that is possible.
Motivation contaminates the results
Maximal tests depend on effort, and effort depends on what the player believes the test is for. A player competing for a place pushes harder than one whose position is secure.
Familiarity also matters, since players who have performed a protocol before pace themselves more effectively within it.
Both effects introduce variation that has nothing to do with the physical quality being assessed.
Injury prediction is the weakest claim
Screening batteries are often justified by their ability to identify players at elevated risk. Injury is comparatively rare and multi-causal, which makes it very hard to predict from a small set of measurements.
Tests that separate groups on average still misclassify most individuals, and acting on those classifications can restrict players unnecessarily.
Any decision about an individual player's risk sits with qualified medical staff who have the full clinical picture, not with a screening score.
The tests still earn their place
Testing establishes individual baselines, which is what makes later comparison meaningful after injury or a long absence.
It also surfaces large asymmetries and obvious deficits that are worth addressing regardless of their predictive value.
The realistic case for pre-season testing is therefore descriptive rather than predictive, and clubs that present it as forecasting are overselling a genuinely useful exercise.