The defeat to Manchester City had many talking points, and there will probably have already been a great deal said about the performance of Arsenal on the day, but for me the thing that sticks in my mind happened before the match actually started.

Per Mertesacker, our best defender – not injured, not really in need of a rest after a whole week since our last game – inexplicably starting the game on the bench with Laurent Koscielny getting the nod. As Arsene Wenger did in our previous biggest home game of the season, he dropped his best defender. And like in the Chelsea game, poor form from Koscielny cost us the game.

Against Chelsea he was at fault for both goals. Against City he hardly lasted ten minutes, getting himself stupidly sent off for effectively rugby tackling Edin Dzeko. To be honest, I’d question whether a red card was necessary with a penalty being awarded, even if it was technically just a referee following the rules – it just seems like something that happens fairly often with a penalty and a yellow deemed sufficient punishment.

Dzeko stepped up and missed the penalty, but with ten men it was always going to be an uphill struggle for Arsenal. We’ve shown before that we can win games against teams with an extra man, but probably never against opposition with the quality of City, who played some excellent football reminiscent of their best stuff from last season. They took a 2-0 lead fairly quickly and could have had more. We were never in the game and for large periods looked like we’d been reduced to five players rather than ten.

Of course Mertesacker did end up playing the vast majority of the game in the end, but why didn’t he start? By the time he was on, he was having to replace Oxlade-Chamberlain as our whole team shape changed to make up for the Koscielny sending off. You could say Wenger has just made the simple decision to use his squad (and why not? Top teams should be able to rotate), but his timing, now for the second time this season in a big game, is what is so questionable. Obviously Koscielny is a good player and could have performed like he did in the first fixture – when he actually played instead of Vermaelen, capping off a solid defensive display with a tremendous and crucial equaliser – but on current form Mertesacker is our best defender and I don’t think there are too many gooners who would dispute that; therefore he HAS to start the big games; there’s absolutely no reason he shouldn’t be. While I understand Wenger rates Koscielny and wants to use his squad, there is a time and a place, and the manager’s judgement of when to do that seems to be flawed, and so it’s not surprising he’s twice been punished for it now.

Is there something else going on behind the scenes? Does Wenger have an agenda that big Per doesn’t fit into? Is he somehow not convinced the German is up to scratch? Is there still something of a bias towards his French players? I hate speculating on things of this kind because it seems almost too easy. I don’t truly believe it when people say that Wenger the Frenchman always has a preference for French players, but it must be said he has obviously plucked more talent (and in some cases non-talent) from Ligue 1 than most teams, except perhaps Newcastle in recent years. Yes it’s cheaper to shop abroad than from rival Premier League clubs, but then there are bargains lurking in Spain and other leagues as well – sometimes even better than in France (Giroud for £12million or Michu for £2million?).

But this is not an article to go into the boss’ transfer policy – the fact is, he made a very poor selection choice having made the very same mistake before. Another notable time he did this in a big game was in the 2009 FA Cup semi-final against Chelsea, when he went for the French Diaby over the in-form Russian Arshavin in the starting XI. We’ll never know why, but it doesn’t help Wenger fight the rumours that he is a control freak who puts his own proteges (who are, coincidentally, often French) before established players who genuinely improve the team.

You make up your own minds.

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