You are 100% right , considering the resources that Arteta had at his disposal vs his competitors nobody was tipping Arsenal for 4th at the beginning of the season.
So if he achieves it it's fair to say that he's over achieved and that deserves praise.
Also this whole "They are only doing well because of the lack of European football" argument is just salty bollox too because;
1. Everyone knew they had no European football at the beginning of the season and nobody made you favorites because of it.
2. No European football isn't the reason your team looks like a cohesive unit. You could have given Ole a month between games and he would have sent his players off for a holiday and they'd still be spamming through balls on counter attacks when they got home.
All these shouts about how it may crumble next year (Err of course that can happen, just like at every other club) due to the addition of European football are ignoring the fact that Arsenal knew they had no European competition to contend with this season and cut their cloth accordingly. If they fail to invest next season then it's a failure on the board not Arteta.
Now that United are out of every completion and only have one game a week I expect them to look like 70s Brazil after the international window.
The same posters who are talking about "Kneejerk reactions" will also be the first ones posting once Arteta loses a game.