David Moyes seemed genuinely crestfallen when Lamine Kone was ruled out of a home game against Burnley at the 11th hour.
It had been against the same opponent months earlier that his substitution sparked a spectacular implosion, a New Year’s Eve horror show from which Sunderland’s season never recovered.
That Moyes was so panicked by this latest knock said much.
Even despite his declining form, even despite everything that had happened at the start of the 2016-17 season, a drama which Moyes never really let go, Kone remained the best defender at the club.
That remains the case, and by a distance. The Ivorian bounced back from a lethargic pre-season with a performance of power and impressive efficiency against Derby.
Chris Martin, generally seen as one of the best target men in the division, was made to look pedestrian.
Few would have predicted that Kone would still be in red and white stripes come the opening day of the season.
After those sparkling first six months in the Premier League, it seemed inevitable that any future relegation would precipitate his departure.
That has not proven to be the case, with Sunderland yet to field any significant interest.
A reunion with Sam Allardyce at Crystal Palace looked a solid bet, but the arrival of Frank de Boer saw more versatile, technically talented defenders pursued. Jairo Riedewald has already arrived from Ajax. Timothy Fosu-Mensah from Manchester United will soon follow.
It would be a major surprise, still, if Kone did not leave before the end of the month.
A number of Premier League sides are in the market for a centre-back, with West Brom, Burnley, Southampton and West Ham will all likely to make additions.
The lack of movement so far makes clear that Kone is not a first-choice option.
West Brom, for example, have pursued Ben Gibson throughout the summer and are now monitoring Thomas Vermaelen.
All of these sides know, however, that, with years left to run on his deal and real talent to be refined, Kone could be a bargain.
It poses a dilemma for Sunderland, who will have budgeted for this summer in the expectation that the 28-year-old would depart for pastures new. Of that they can no longer be entirely certain.
Kone’s future clearly has significant implications for the make up of new boss Simon Grayson’s defence, an area that has perhaps been his biggest concern since arriving on Wearside earlier in the summer.
His admission that he feared another collapse after Derby took the lead last Friday reflected a back line that has not inspired confidence for some time.
Leadership and experience are required, with Tommy Elphick an obvious candidate, but Kone’s departure would also leave the back line looking short of pace and power.
Put simply, his future has significant implications for the rest of Sunderland’s transfer business.
That excellent display against Derby County has at least demonstrated to Grayson, who has handled the situation superbly, that, for the time being, he can call upon a player of superb talent at this level.
Beyond that things are still, surprisingly, very much up in the air.