Rotate the runners and leave your back pair alone

Squad rotation is treated as a fitness exercise when the real constraint is which relationships on the pitch cannot be rebuilt weekly.

Not all positions cost the same to change. That is the sentence missing from most rotation policies, which treat eleven shirts as eleven interchangeable slots to be filled according to who has played the most minutes.

Two centre backs and a goalkeeper are a communication system. They work on a shared understanding of when one steps, how far the line pushes, who talks at a corner and whose voice wins when two people call the same ball. That understanding is built over months and it degrades fast when you break the pairing, which is why teams who rotate their back line are prone to a specific kind of goal: the one where two defenders both go, or neither goes, and a striker walks between them looking slightly surprised.

Midfield runners and wide forwards are the opposite. Their job is largely individual output within a pattern that can be explained in a team meeting. Swap them and the shape survives. You lose a little chemistry in combinations and you gain a fresh player in the roles where freshness converts most directly into output, because pressing and repeated sprinting fall off a cliff with fatigue while positional discipline does not.

So the policy writes itself, and yet clubs keep doing the reverse, because the front players are the expensive ones and the manager wants his best attackers available for the big match. Then he rests a centre back against a mid-table side on a Wednesday, concedes twice, and calls it complacency.

I would push the principle further to include set piece assignments. Every change to the back line rewrites two or three marking jobs, and defensive corners are where an unfamiliar pairing is punished hardest, because there is no time to work anything out and no ball to watch except the one arriving.

The honest complication is that centre backs get injured and suspended anyway, so a pairing that never plays apart is fragile in a different way. My answer is to have a third defender who trains with both of them constantly and plays perhaps a dozen matches, chosen deliberately rather than by emergency.

Rotate the legs. Protect the conversations. Those are not the same category of thing and most squads treat them as if they were.