Minutes played is a terrible unit of work

Squads are managed by the clock because the clock is easy to count, and two players with identical minutes can be in completely different states.

Ninety minutes as a full back in a team that defends a low block and counters twice is not the same job as ninety minutes as a full back in a side that presses high and holds the ball for two thirds of the match. Everybody in football knows this. Almost every squad is still managed as if a minute is a minute.

The reason is administrative rather than intellectual. Minutes are unambiguous, they appear in every database going back a century, they can be compared across leagues, and no fitness coach has to defend them in a meeting. Any better unit is contested. Exposures above a speed threshold depend on where you set the threshold. Accelerations depend on the sampling rate of the device. Distance covered in possession versus out of possession requires somebody to sync tracking with event data and to agree on what possession means.

So clubs count the thing that is countable and then apply intuition on top, which is fine until the intuition belongs to a manager who needs a result on Saturday.

If I had to pick a single replacement unit I would choose high intensity efforts with a change of direction, counted per match and rolled over four weeks. Not because it is perfect, but because it correlates with the movements that actually break players, and because it separates the two full backs in the first paragraph immediately. One of them might be at forty per match. The other at twelve. Same minutes on the team sheet.

The complication that nobody solves neatly is travel and sleep. A player who flies eleven hours for an international, plays, flies back and trains on Friday has accumulated a physiological cost that no tracking vest records at all, and there is decent reason to think that cost is larger than the football itself. Clubs know this and have essentially no say over it, so it goes into the column marked bad luck.

Here is the thing that bothers me. Every year somebody publishes a study saying congested fixtures raise injury rates, and every year the response is a call for a smaller calendar, which is not happening. Meanwhile the unit of measurement stays wrong.

Fix the unit first. You cannot argue about the schedule with a number that treats standing in a wall as work.