Oscar Wilde was rarely wrong about these things. As the great wit and playwright so famously wrote: to lose one lead against a 10-man Arsenal side may be accounted a misfortune. To lose two leads, however… well, people are going to start accusing you of carelessness.

When Dave tapped in that cross in the 84th minute, it was all over, wasn’t it? We’d already gifted an under-strength and mostly exhausted Arsenal one goal; we couldn’t possibly gift them another one, even if there were an adequate amount of time left in which to do so. The points were as good as salted away, and we were all set to continue a run of consecutive home victories stretching all the way back to Nottingham Forest in the FA Cup third round a fortnight ago, thereby banishing for good these absurd mutterings about a ‘home hoodoo’.(Surely the struggles to find consistent form at home have had less to do with the feng shui at Stamford Bridge than with a young side’s teething problems in relation to breaking down visiting teams content to stick 10 men behind the ball. Which, in Arsenal’s case, was all the men they had.)

But no. Football is an absolutely terrible game: fact. The referee for once chose to ignore the fact that a player was flat-out in the middle of the pitch, several different shades of shambles took place on the left side of our defence, and suddenly the score was even again.Gobsmacking. And somehow defying all known norms. For instance, I don’t keep too many tabs on who generally scores the game-saving goals at Arsenal these days, but my impression from a distance is that it isn’t Hector Bellerin. Shades of Nigel Winterburn, then, who scored less frequently than southern England experiences white Christmases, yet who somehow found the wherewithal to clobber in a sickening winner against us here in 1997. Shades, too, of 1999/00 and Kanu, who rarely seemed to be Arsenal’s busiest player, running up a hat-trick in 15 minutes to turn an entirely comfortable 2-0 home victory into an utterly miserable 2-3 embarrassment. I don’t know why it should be, but something about playing us here causes these Arsenal people to dig deep inside themselves and do things they wouldn’t ordinarily do. Almost like it’s personal or something.

Mind you, other aspects of the night were very much business as usual. That was the third penalty that David Luiz has given away this season, meaning he currently tops the Premier League ‘giving away penalties’ charts. We congratulate him. And Jorginho continued on a hot streak from 12 yards. There are a lot of moving parts in that penalty action of his (the little skip, the stuttering in the run-up) which, for me, make it a slightly scary watch. But the fact is, since the misery of the Carabao Cup final shoot-out, he’s been unerring. Also, I thought Jorginho’s thing was sending the keeper off on a fool’s mission to one corner of the net and then gently putting the ball in the other one. But no. It’s more varied than that, clearly, and even more bomb-proof. As we found out on Tuesday, the keeper can go exactly the right way at exactly the right speed and still not get anywhere near it.

Of course, we probably should have added at least three more before a patch of black ice claimed N’Golo Kante in the second half, plating up an equaliser that Arsenal had looked unlikely to score in any strictly non-slapstick circumstance. But no. And thus the dispiriting night unfolded.The odd, and consoling, thing, is that even after these tiresome setbacks (Bellerin’s implausible strike coming hot on the heels of Isaac Hayden’s streaky 94th-minute header at Newcastle last Saturday), we remain relatively comfortably embedded in fourth place, in a season in which, with one glaring exception, everybody keeps finding new ways to disappoint themselves.

It’s hard not to reflect ruefully, though, on the unbridgeable chasm – an ocean indeed - that could now be separating us from Manchester United and Wolves in the Champions League places if even just a handful of moments had gone closer to plan. But, exasperatingly, what keeps costing us is dropped points against teams from lower down the table: your Newcastles, your Southamptons, your Arsenals. Ah, well. Beyond the FA Cup this weekend lie two top-end teams: Leicester and Manchester United. And then perhaps we’ll see where we really are. Or maybe not. It’s that kind of season.

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