Rotate the front three and leave the back four alone

Squad rotation is priced in minutes when it should be priced in relationships, and defensive partnerships are the expensive ones to break.

Rotation gets discussed as though all eleven shirts cost the same to change. They do not. Swapping a winger costs you a set of individual qualities. Swapping a centre back costs you a set of agreements, and agreements take months to build and one afternoon to lose.

The difference is about what the job consists of. An attacker's job is largely improvised. He receives the ball in a rough area and decides. A fresh player can do that on his first appearance, and sometimes better, because he is not tired and the opposition full back has not seen him before.

Defending in a back four is a coordination problem with no ball involved. When the line steps, all four step, at the same moment, based on a shared read of a passer nobody is close to. When one drops a yard late the offside line breaks and the goalkeeper is exposed. That timing is not really coachable in the abstract. It gets built by repetition between specific people, and every substitution resets a piece of it.

So the sensible rotation policy is asymmetric. Change the front three freely, weekly, aggressively. Protect the spine. If a centre back has to be rested, rest him alongside his usual partner rather than dropping a new man into a pairing, so at least the pair is intact even if the pair is second choice.

I know the objection. Defenders get injured too, and hamstrings do not care about partnership continuity, and a fatigued centre back is slower into a duel he has to win. All true. My claim is about the order of operations. When a manager is deciding where to spend his three or four changes in a congested week, the last place he should be spending them is across the back line, and quite a lot of teams spend them there first because the fixture looks easy.

Fixture difficulty is the wrong input anyway. You do not rotate against weak teams because they are weak. You rotate to protect a match three days later.

Watch the first fifteen minutes after a new centre back partnership is introduced. The line is always a yard deeper. Nobody trusts anybody yet.