If you must rotate somebody, start with the full backs

The wide defender covers more ground at higher intensity than anyone on the pitch, yet he is the last player managers rest.

Rest the striker and everyone nods. Rest the goalkeeper and it is a talking point for a week. Rest the right back and nobody notices, which is roughly the inverse of how the physical demands actually distribute.

The full back's job has expanded to the point of absurdity. He is expected to provide the width in possession, which means starting most attacks from the touchline sixty metres upfield, and to be the first line of defence against the counter down that same flank, which means covering the entire distance back at speed with no rest in between. Add the tactical fashion for stepping inside into midfield and the role now involves changing direction constantly rather than running in a straight line, and direction changes are what break people.

So when a squad is planning a heavy run of fixtures across a league phase and a domestic season, the position that most needs two genuine options is the one clubs most often staff with a starter and a teenager. Centre backs get rotated because they are easy to replace like for like. Midfielders get rotated because there are five of them. Full backs get run into the ground because the backup is not trusted and because the position looks less demanding than it is.

There is a tactical benefit as well as a physical one. Two full backs with different profiles, one who overlaps and one who steps inside, is a real weapon across a season, and having both means the shape of your attack can change without changing anyone in midfield. Teams that carry that pair look flexible. Mostly they are just fully staffed.

The objection is that defensive partnerships need familiarity, and rotating a full back disturbs the back four's understanding. That is true and it is smaller than the alternative, which is playing your best wide defender sixty matches and losing him in April.

The player who never gets a rest is not your most important. He is your least replaceable, and those are not the same thing.