There is a line supporters and pundits often reach for when a Championship side is struggling to score: "defence wins titles." It is a cliché, but it contains something real. Most teams that have pushed for promotion in the second tier have done so with a defensive unit that knew itself well, covered for one another instinctively, and made the opposition work hard for every chance. Derby County, at present, look nothing like that kind of side.

According to a fan piece published by BBC Sport, Derby have not named the same back four in consecutive matches since 29 August. That is a remarkable statistic at any point in a season, let alone one in which the club has just endured three successive defeats. Since the campaign began, eight different players have featured across the defensive line in various permutations: Max Johnston, Joe Ward, Ryan Nyambe, Dion Sanderson, Sondre Langas, Eiran Cashin, Charlie Taylor, and Craig Forsyth. Manager John Eustace, it seems, has yet to settle on a first-choice combination he trusts.

The evidence from Saturday

The Birmingham City defeat at the weekend offered a pointed illustration of where the problem lies. For the equaliser, Taylor was drawn out of position by a run from Carlos Vicente, drifting into the same space already occupied by Cashin. The covering attempt came too late, and Vicente headed home at the far post. It was the sort of miscommunication that a settled partnership tends to eliminate over time. Two defenders who have played together regularly will have already negotiated who takes the runner and who holds the line. These two had not.

The second goal was, if anything, more troubling. Langas became so fixated on monitoring Christoph Klarer in the penalty area that he lost sight of the delivery from the corner entirely, leaving Paik Seung-Ho completely unmarked to score an uncontested header at the far post. Goalkeeper Jacob Widell Zetterstrom was effectively stranded. That kind of defensive breakdown is rarely about individual quality alone; it speaks to a unit that has not yet worked out its responsibilities on set pieces.

The piece also notes that Derby were perhaps fortunate the scoreline was not worse. Birmingham were not especially clinical, and a more composed visiting attack might have turned what became a 2-1 defeat into something considerably heavier.

Injuries are part of the picture, but they are not the whole story

Eustace does have genuine mitigation. Long-term injuries to Derry Murkin and Matt Clarke, last season's player of the year, have deprived him of two players who would, in normal circumstances, be near-certainties to start. Losing your most reliable defensive performer for any extended period causes disruption that cannot simply be rotated away. The Rams have had to mix and match not out of tactical curiosity but out of necessity.

That said, necessity does not remove the urgency. The longer Eustace delays settling on a combination from the players available, the less time that group has to develop the kind of understanding the division demands. Other clubs in the Championship have had to cope with injuries without allowing their defensive shape to become a guessing game from week to week.

The attacking progress counts for nothing yet

There is some encouragement in how Derby have been playing further forward. The piece acknowledges more positive patterns in the final third and greater urgency in attacking areas. But a team that cannot keep the ball out of its own net will not rise up the table regardless of how well it creates chances. The Rams' attacking drought was a concern explored in these pages recently; the defensive fragility now rivals it as the more pressing problem.

Three defeats in a row. Eight defenders rotated through the back line. An injury to the reigning player of the season. Derby's situation is not yet a crisis, but the ingredients for one are clearly present. Eustace needs to pick his best available four, commit to them, and let them grow into the unit this club requires. Press-release talk of "building a platform" means very little until the back four can hold a lead.

Frequently asked

Why has Derby County kept changing their back four this season?
Long-term injuries to Derry Murkin and Matt Clarke, last season's player of the year, have forced manager John Eustace into regular changes. Derby have not named the same defensive four in back-to-back matches since 29 August.
How did Derby concede against Birmingham City?
Both goals stemmed from defensive confusion. The first came after a miscommunication between Charlie Taylor and Eiran Cashin that left Carlos Vicente free to head home. The second was a simple far-post header from Paik Seung-Ho, who was left completely unmarked from a corner.
Which Derby defenders have been used this season?
Max Johnston, Joe Ward, Ryan Nyambe, Dion Sanderson, Sondre Langas, Eiran Cashin, Charlie Taylor, and Craig Forsyth have all featured in Derby's back line during the current campaign.