I thought Arsenal should've dropped Ozil and switched to 3 in midfield. I don't think they can play a 2 man midfield with Arteta as one of the 2. At the very least, I thought Ramsey should have played instead of Cazorla. At least Ramsey would have brought a bit more energy, running and defensive work. Cazorla and Arteta together was asking for trouble.
Giroud is having a rough start to the season. Letting his frustrations get the better of him and digging himself a deeper hole. Badly needs a goal or two to snap out of this funk. Was so close with those two early chances too ... things not going his way at the moment.
This loss might be a good thing for Arsenal heading into the weekend game against Chelsea. Arsenal (manager + players) seemed over confident about their chances with all the troubles Chelsea have been going through to start the season. I think this loss will do Arsenal some good. Keep their feet on the ground. Make them realize how much more work they need to do to be ready for Chelsea.
You forgot to mention how poor Debuchy and Gibbs were. It could rust, but I don't think so. Bad defending all around.
Giroud was an idiot.
And the fact that Wenger didn't buy a competent CM to dispel Coquelin is now being exposed. Now it's looking like Coquelin has to play every game until the January window, atleast. No defensive presence on the midfield at all.
It was a poor performance all around, it's frustrating. Zagreb didn't do anything special, both goals were handed to them on a plate from bad defending.