Rotate anybody you like, but leave the centre-backs alone

Squad rotation is sensible almost everywhere on the pitch, and quietly disastrous in the one place that depends on habit.

Rotating a striker is fine. He is going to run the same channels, make the same near-post movement, and finish what he is given. Rotating a winger is fine, arguably good, since fresh legs against a tired full-back is a genuine advantage. Rotating a goalkeeper for a domestic cup tie is a tradition and nobody has ever proved it costs anything.

Rotating a centre-back pairing is different in kind, not degree.

What two centre-halves do together is almost entirely non-verbal and it is built on repetition. One steps out to meet a striker dropping short and the other slides across to cover, and the timing of that slide is calibrated to a specific colleague's speed and a specific colleague's tendency to over-commit. The offside line depends on both of them stepping at the same instant, which they cannot signal in a loud stadium, so they do it on a shared sense of when the ball is about to be struck. That is not tactical knowledge. It is a habit that takes months to build and about one match to disturb.

Break up a pair and you get the same symptoms every time. Two defenders both stepping out to the same forward. A line that goes up in a curve rather than flat, playing somebody onside by two metres. Communication that becomes explicit and therefore slow, one of them shouting an instruction that would previously have been assumed.

The full-back to their outside gets caught in this too. He is timing his own step off the man beside him, so a change at centre-half quietly makes the whole line worse, not just the middle of it.

I would go further. If you must rotate a defence, change one at a time and keep the same holding midfielder in front of them, because he is the reference point for the entire defensive block and half the coordination runs through him. Changing the pair and the six in the same match is asking for a bad afternoon, and the goals it produces will get blamed on individual errors rather than on the selection that caused them.

Which is the annoying bit. When a rotated defence concedes twice, the analysis lands on the young man who was caught out of position rather than on the fact he had never played next to that person in a competitive match. He gets a reputation. The team sheet that created the situation gets none.

Rest people. Just rest them in ones, and not from the same partnership.