Arsenal won their first league game of the season last Friday, despite playing a winger at left–back, a left–back at centre–back, another left–back at centre–back, and without the services of their captain, best centre midfielder and best attacker.

It’s important that the above paragraph is posted at the start of the article, because despite so many things going wrong for Arsenal during that game, this statement holds true. Arsenal won a competitive game against a good opponent without the help of a lot of players that they would normally rely on, and did so whilst also highlighting a number of flaws in their game. Overall, Arsenal should be happy with the result, but should a performance with as many unforced errors in it be cause for concern?

In short, no.

Obviously, it would be great if Arsenal were better than average in every facet of play, but the simple matter is that there isn’t enough time for Arsenal to train for every scenario. The same applies to every club, of course, and each club allocates their time to matters that they consider to be important, but at the heart of every coaching decision made is the following choice: What matters more to us, scoring goals or not conceding them?

It may sound like over–simplifying the issue, but Arsenal don’t have the time to work on complex passing drills, film work to study what runs to make for other players, learn a completely new formation AND have enough time left to do enough work on set pieces to be well drilled enough to cope with other teams who spend far more time on them than Arsenal do.

Just look at Leicester’s first and third goals as examples. Credit to @arsenalist for the clips.

Watch Alex Oxlade–Chamberlain for the first goal. He’s supposed to mark the near post, but the corner is taken quickly and he wanders into the penalty box, with no idea what to do. When the ball goes in, he’s standing on the penalty spot, hoping for a chance to counter instead of trying to defend, because he’s a winger not a full back.

Now watch Oxlade–Chamberlain for the third goal. Again, he’s on the near post, but this time he reacts to the possibility of a short corner being taken, and rushes out to prevent it. Here’s where the difference between spending some time practicing set pieces and spending a lot of time on set pieces stands out, because Leicester react to seeing the man who should be covering the near post leave his area, change what they were planning on doing, which was another short corner, and play the ball directly into the area that the Ox should have been able to help defend, and make everyone run into that area in the hope of one of them getting a free run. Jamie Vardy is the one who is left free, and he scores.

Leicester’s third goal was a clear indication of what they spend a lot of time practicing, and what Arsenal don’t. But this is something that will always be the case. The argument for using a zonal marking system is never decided by how effective you can make it, but instead it’s a case of how much time do you want to spend on set piece training. Almost all the major European teams use zonal marking, not because it’s better than man marking, because of the reduction in time it takes to train for it. The only exceptions are Juventus, who had the best defence in the world last year anyway, and Manchester United, who have a manager that obsesses about not conceding goals.

Should Arsenal spend more time on set pieces? Perhaps. This article from @mixedknuts is certainly a good argument for doing so, but to truly exploit set pieces to their potential, like West Brom and Atletico Madrid do, then you’re left with a game plan that focuses on getting more set pieces and not more opportunities from open play. My principal argument for not wanting Diego Simeone as a successor to Arsene Wenger wasn’t that he isn’t a talented manager, but that the football he gets his teams to play is awful to watch. Yes, it’s effective, but is that enough?

The price we have to pay for wanting to see Arsenal score goals like the second one against Leicester is that we’re going to be vulnerable to conceding goals like the first and third ones. We have to accept that giving Granit Xhaka the freedom to create goals with the sort of pass that assisted Arsenal’s third goal is occasionally going to lead to Xhaka giving the ball away like he did for Leicester’s second goal.

Arsenal were always going to be susceptible to set pieces, and even more so with such a patched–up backline as the one they fielded last Friday. But even when the likes of Laurent Koscielny and Shkodran Mustafi return to the starting line–up, Arsenal will still look unprepared in relation to the vast majority of sides they face this season. This is something that we need to get accustomed to, because this is by design.

Will that stop us moaning every time an opposition player gets a free run in our penalty box during a corner? Of course not, but the fact is that Arsenal are going to spend virtually no time all season on set pieces, and still rely on Olivier Giroud to try and score from one, even with one defender trying to rip the shirt from off his shoulder and another defender trying to chop him down by the knees.

It’s going to be a long season.