A week ago this piece would have looked very different. A week ago, Arsenal had just beaten Cologne after switching to a back four at half-time and were widely expected to meekly lose to Chelsea at Stamford Bridge.

Another defeat like the one at Anfield a few weeks ago would have almost certainly seen Arsene Wenger revert to type, banishing the back three formation he never really believed in anyway and returning to the tried and tested 4-2-3-1 on a more permanent basis.

Contrary to all expectations, an Arsenal side bereft of Alexis Sanchez and Mesut Ozil put in a brilliant performance, stifling Chelsea for the most part and threatening enough (at least in the first half) to deserve a point at the very least. Suddenly, from the brink, the 3-4-3 definitely has a place.

That should probably be the root of some optimism but also concern; it feels a lot like Arsenal will continue to blindly stumble around in a particular constellation until that goes so badly so many times in a row there is little option but to change again. Repeat ad nauseam.

While the 3-4-3 has its place, it should just be one way the team can play and it is – as we’ve seen – much better suited to games against big sides (like Chelsea in our last three meetings), and games against teams who line up in a similar fashion (like Bournemouth).

This weekend’s fixture against West Brom is the perfect time to show Arsenal can adapt and be flexible according to the available squad and the needs of any given game.

Barring two (if memory serves) drubbings right at the end of the season (2009 and 2015), home matches against Tony Pulis have always looked the same: Arsenal dominate but hardly create, Arsenal eventually score a half chance and the game ends 1-0 or 2-0 in relative comfort.

It’s not usually pretty but this is a tricky fixture and one we’ve never failed to win. It’s actually true of Arsenal across the board in these ‘simpler’ matches that the team doesn’t disappoint: the rate at which we’ve picked up points in home games we ‘should’ win is on par with all our competitive rivals at the top of the table. If it ain’t broke, don’t fix it.

The squad situation also does a lot for the argument we should return to playing four defenders when it’s most suitable. Games are now coming thick and fast and there needs to be some rotation at left-back: as things stand, both Nacho Monreal and Sead Kolasinac will play almost every single game.

Monreal is the first choice left centre-back as well as being the back-up left wing-back, the opposite applies to our lovable Bosnian brute. With the Europa League coming up in midweek, more League cup games on the horizon and two international breaks before December, the pair will each have to miss some matches.

Then there’s Danny Welbeck. After pre-season I touched on how important he was for the front three in pressing. Since then, his performances have impressed and his influence has grown. Playing on the right of the front three, Welbeck ties up at least one defender by driving forward and becoming a second striker. Occupying defenders allows him to team up with Lacazette so the duo can either spark moves or create space for one another. See the opening two goals against Bournemouth as an example.

It goes without saying that Alexis Sanchez is a fine player but, as we saw in recent fixtures, he can drop extremely deep for the ball. With Alex Iwobi or Mesut Ozil doing the same on the opposite side, Arsenal quickly lack enough players occupying the opposition high up the pitch (interestingly, this is why it is probably best for Theo Walcott to play on the opposite side from Alexis, a tactic which looked like Arsenal’s only viable route to goal against Doncaster in midweek).

With Alexis and Ozil both expected to return to the side, Arsenal will need all the numbers they can get in dangerous areas against a stubborn West Brom defence. That could be the case in the 3-4-3 but not the way Arsenal play it with both Alexis and Ozil, who drop deep and leave an onus on Ramsey to drive at the opposition backline.

Wenger has quickly changed during games where Arsenal are stifled and appears to be becoming increasingly impatient. Last season the boss switched back to 4-2-3-1 in minutes 68 (Leicester) and 69 (Sunderland). We saw the same pattern in the opening two games of this season, with the change taking place in the 67th (Leicester) and 66th (Stoke) minutes.

Four games is no real sample size but the evidence to this point suggests the change in tactic is hit and miss; a roll of the dice rather than a piece of ingenuity. Thanks to @11tegen11, we can see the the changes made a difference against a tiring relegated Sunderland and to lesser degree against Leicester made a difference, with Arsenal creating chances more frequently.

The same can’t be said of the games against Leicester (last season) and Stoke.

The situation against Cologne, calling upon Kolasinac at half-time, was completely new. It was the right call but a strange one – Arsenal had the players for this system on the pitch throughout the first half, why wait until half-time? It immediately paid off with Kolasinac scoring but the biggest difference came from Alex Iwobi. Finally Arsenal had a player getting between the defence and midfield, looking to increase the pace of the game and move forward quickly every time he got on the ball.

That’s what’s needed to break this sides down. Instead of wasting time with the 3-4-3 only to switch, Arsenal should start with a back four and go after West Brom with a little more verve and an extra player in dangerous areas, be that someone to make runs beyond Alexandre Lacazette or just to pick the ball up behind him.

A week after the game at Stamford Bridge was likely to put a nail in the back three’s coffin, it’s probably likely to be the game against West Brom that has Wenger cursing his luck and wondering if it’s the way to move forward. The truth is, of course, that Arsenal should move forward with the ability to play both systems.

Having two formations which suit the players is an incredible and long overdue string to Arsenal’s bow but it’s an obsolete one if we are only using it to become predictable in a different way. All the tools are there, now’s the time to use them. Be flexible and thrive.