Top speed figures circulate as though they were fixed properties of a player. They are outputs of a measurement process, and that process varies enough to change the answer.
Sampling rate sets what can be seen
Positional systems record a player's location at fixed intervals and calculate speed from the change between samples. A higher rate captures brief peaks that a lower rate averages away.
Satellite-based units, local positioning systems and optical tracking all operate at different rates. The same sprint therefore yields different peaks depending on which system recorded it.
Differences of this kind are systematic rather than random, so one system may consistently report higher figures than another.
Smoothing removes noise and peaks together
Raw position data contains error, and speed calculated directly from it jumps around implausibly. Every system applies filtering to produce a usable trace.
Filtering necessarily reduces short-lived extremes, because it cannot distinguish a genuine peak from a spike of noise. Heavier smoothing produces cleaner data and lower maximum values.
The filter settings are usually proprietary, which means the adjustment applied to a published figure is not visible to anyone reading it.
Environment degrades some methods more than others
Satellite positioning depends on signal quality, which stadium roofs, stands and weather all affect. Coverage inside a bowl-shaped ground is worse than on an open training pitch.
Optical systems depend on camera calibration and clear sight of the player, so occlusion in crowded areas creates gaps that must be interpolated.
Both methods have conditions where they perform poorly, and those conditions differ, which complicates any attempt to combine their outputs.
The definition of a sprint is a choice
Deciding whether a run counts as a sprint requires a speed threshold and usually a minimum duration. Both are set by convention rather than by physiology.
Individualised thresholds based on a player's own maximum give better within-squad meaning but make published counts incomparable between clubs.
Sprint counts quoted without their definition therefore convey very little, even though they are among the most frequently cited figures in the sport.
Comparison needs a shared protocol
Meaningful speed comparison requires the same system, the same settings and ideally the same surface and conditions. Those requirements are rarely met outside a single club.
Some competitions have standardised on a single provider for match tracking, which makes within-competition comparison sound and cross-competition comparison no better than before.
The honest reading of any top speed figure is that it describes a run measured a particular way, which is a narrower claim than the way such numbers are usually presented.