Alan O’Brien  Follow @alanob2112

Back in August, Antonio Conte deviated from his title-winning 3-4-2-1 system for a big game just like this one. Tottenham Hotspur were frustrated, and bested, by a more conservative Chelsea 3-5-2. Its inception was designed to ensure greater defensive security against stronger sides. Yet, on Wednesday night, in another London derby, it achieved anything but.

Bakayoko

Tiemoué Bakayoko has a lot to answer for, in that regard. An alleged upgrade on the departed Nemanja Matic, Bakayoko evidently lacks the Serbian’s unrivaled positional intelligence.

Both of Thibaut Courtois’ big first-half saves followed from the ease with which Mesut Ozil drifted goal-side of the French midfielder. One tactical error is forgivable, but a continual succession — in a game of this magnitude — is not.

Particularly when the reasoning behind Bakayoko’s inclusion is considered. When Conte’s peers cottoned on to mimicking his seemingly invincible 3-4-2-1, its initial wild success was significantly curtailed. So influential was the Italian’s idea, that even the famously dogmatic Arsene Wenger deserted his beloved back-four.

Mimicry

Configured in Conte’s system, Arsenal outplayed Chelsea throughout May’s FA Cup final, and August’s Community Shield. Big-game sacrifice was called for, in the Italian’s eyes. One of the 3-4-2-1’s two inside-forwards became the lamb, replaced by an additional central-midfield body. Enter Bakayoko.

Early results were promising, with Tottenham, Atletico Madrid and Manchester United all falling victim. The 3-5-2’s more counter-attacking outlook, primed with two centre-forwards to dovetail on the break, looked potent. Conte’s favourite word was back in vogue: ‘balance’.

But cracks soon appeared in the defeat to Manchester City. The fortunate draw with Liverpool, inspired by a late switch back to 3-4-2-1, followed. Bizarrely, Conte kept the faith with his new system, however, even when faced with much weaker opposition. December’s shock defeat at West Ham United owed much to the central congestion Bakayoko’s then-unnecessary presence promoted.

Not that his presence was not called for here, up against an imperious Ozil. Unfortunately for Bakayoko, and for Conte, Wenger’s mimicry had struck again.

Surprise

Widely expected to line out in the now customary 3-4-2-1, Wenger surprisingly plumped for a 3-5-2 of his own. Which meant that Cesar Azpilicueta had Alexis Sanchez to worry about, preventing the centre-back from rushing out to confront Ozil — as, presumably, planned.

Arsenal, as usual, were suffering structural problems of their own, however. Their forwards’ high-press, also a feature of September’s drawn reverse fixture, certainly disrupted Chelsea’s possession-play. But, the glaring deficiencies of the depleted ranks behind were also brutally exposed.

On three distinct occasions, in minutes 14, 70, and 93, Alvaro Morata found himself clean through on goal from a simple long pass. On each occasion, the woefully wasteful Spaniard fluffed his lines, sparing the blushes of the likes of Calum Chambers and Rob Holding.

Arsenal’s keenness to harry the Chelsea defence also regularly stranded holding midfielder Granit Xhaka. With both Ozil, and Jack Wilshere, slow to assume their defensive positions, Cesc Fabregas had a field day; his dominance only outstripped by Ozil himself. Bakayoko, running off the German, should have profited from at least one of Fabregas’ first-half through-balls.

Inertia

The irony of two 3-5-2s making for such an open, chance-laden, encounter was surely not lost on both managers. And, yet, the madness persisted in the early stages of the second-half. It was in this period that Arsenal fashioned their only clear-cut chance of the game, when Ozil — again free in the pocket behind Bakayako — played Alexandre Lacazette through. Still, Conte was unmoved.

Eventually, the Italian was punished for his inertia. An unbelievably cheap giveaway from Bakayoko led to the set-piece from which Wilshere, eventually, beat Courtois at his near-post.

Indeed, it was Wenger who produced the first tactical blink, after Eden Hazard’s penalty-kick equalizer. Going for broke, the Frenchman switched to a more open 3-4-2-1 system, replacing Lacazette with wide-forward Danny Welbeck.

Mimicry (again)

Fatally, Conte took the bait. The desire to frustrate Arsenal’s 3-4-2-1, the reasoning behind selecting a 3-5-2 in the first place, was forgotten. A spent Hazard, who followed six first-half dribbles with none after the break, was sacrificed for Willian.

The Brazilian joined Bakayoko in the inside-forward slots of a 3-4-2-1. N’Golo Kanté, tireless as always, found himself alone with Fabregas; a state of affairs that did not work out well for Chelsea throughout September’s reverse fixture.

Where once there stood three central midfielders, there now stood two. And, although Marcos Alonso grabbed Chelsea a late lead, Hector Bellerin nabbed a last-gasp equaliser from that very zone.

Wenger’s last roll of the dice, an 88th-minute switch to 4-4-2, had paid off handsomely, frightening Chelsea’s defence back to their own six-yard line.

Conclusion

Bellerin’s goal, followed by the third of Morata’s shocking misses, was a fitting conclusion to a madcap, control-free, encounter. An encounter that greatly damaged the 3-5-2’s burgeoning reputation.

As a reactive, deep-lying, system, it’s fine. But, when one looks to defend high and press, as both sides did here, the central midfield chasms — either side of one’s holder — are hard to plug.

Neither Wenger, nor Conte, managed it here. The game finished level, but ultimately the neutral viewer was the clear winner. Bakayoko, whose Chelsea raison d’etre is now in serious question, was very much the loser.

Follow the author, Alan O’Brien, on Twitter:  Follow @alanob2112