Arsenal were 3-1 up at the Emirates against Tottenham, deep into the kind of afternoon a manager dreams about handing to his fringe players, and Mikel Arteta made four substitutions all season could have used as evidence for restraint rather than reform. Four changes, from a position of total control, in a fixture that exists specifically to be the one you can afford to manage. It was not an isolated data point. Arsenal went 4-1 up against Spurs earlier in the campaign before Arteta made a single change. Against Burnley, comfortable wins offered obvious openings at full-back that went untaken. Against Atlético Madrid in the league phase, Arsenal led 4-0 and Arteta waited until the seventy-second minute to make his first change. Somewhere between what Arteta says about his squad and what he does with it, there is a gap.

The story that has been told about this Arsenal side, and told well, is that Arteta has built a squad in which reputation counts for nothing and every name on the sheet can start on merit. It is a good story, and it has the merit of being true in the sense that it describes an ambition rather than a lie. It also has the convenience of arriving at exactly the moment Arsenal needed it, because Bukayo Saka, Martin Ødegaard, Kai Havertz, Mikel Merino and Jurriën Timber have all missed significant time this season, and a club that had not built genuine depth would be nowhere near where Arsenal currently sit: six points clear at the top, into the Champions League semi-finals, still standing after a run of injuries that would have finished off most title efforts by January. That is not a small achievement, and anyone arguing the rotation policy has failed needs to explain that scoreboard first.

So the derby matters, and Burnley, and the first Spurs game, and Atlético. Depth forced upon you by injury is not the same thing as a rotation policy chosen in advance, and the evidence from the games where Arteta actually had a choice suggests the policy is thinner than the reputation. When Arsenal have been four goals up with time to spare — the precise circumstance rotation is meant to solve — Arteta has kept his first-choice spine on the pitch anyway. Declan Rice does not come off. Riccardo Calafiori did not come off, not often enough, and neither did Timber, and both have since spent time in the treatment room in a way that invites the obvious hypothetical: whether a manager less attached to his best XI in games already won might have arrived at April with fresher legs and fewer names on the physio's list. It is impossible to prove a counterfactual. It is not impossible to notice a pattern.

There is a version of this argument that turns into the tired one about squad harmony, the idea that changing personnel disrupts some mystical understanding between eleven bodies that can only be built through repetition. I do not believe that, and the record does not support it either — teams that rotate heavily have won plenty, and teams that never change a settled XI have collapsed under exactly the fatigue Arsenal are now flirting with. The chemistry argument is usually a way of avoiding a simpler one, which is that legs get tired and joints get sore regardless of how well two players understand each other's runs. Arsenal's problem this season has not been unfamiliarity. It has been the same eleven or twelve players absorbing minutes in games that did not require it, and the bill for that arrives later, in the fixtures it can least be afforded.

Those fixtures are now. Manchester City, Atlético Madrid again, Newcastle — three matches in short order with nothing spare in any of them.

Rice will play all three if his body allows it, because there is no version of Arteta's thinking in which Rice does not play. The rotation policy that was supposed to have banked freshness through the autumn now meets a run of games with no capacity to bank anything at all, and the squad depth that got Arsenal to six points clear will be tested not by whether it exists on paper, but by whether it was ever actually used when it mattered least.

The programme note for this season, if such a thing existed, would probably have called the squad the deepest Arsenal have fielded in years, and it would have been right. What it would not have told you is that a deep squad managed like a shallow one produces the same tired legs in March that a shallow squad always did. Arsenal have spent all season being praised for a rotation policy that the team sheets, checked against each other, say was mostly theoretical until injury made it compulsory. The reputation was earned in the transfer market. The evidence is in the substitutions column, and it reads: seventy-second minute, four goals up, first change of the afternoon.