It's normal, Ozil has no work rate even more since some years ago. And with Arteta's style, assuming because he was with Pep and from what I have seen so far, the team needs players that don't slack defensively so the press can work. This doesn't succeed with players like Ozil.
In relation to Emery, I know he didn't have the best team at Arsenal and that english fans usually defend him a lot (seeing from Reddit), but I (and a lot of portuguese people) think he's a hoax (don't know if the word is correct just saw the translation in google translator). Dude apart from Valencia never did quite good in the league nor he showed tactical glimpses of being a top tier manager. He won 2 or 3 Europa Leagues, but his tactics were never that ambitious to begin with and that showed in the league table across his time at Sevilla. Once they got rid of him and got Sampaoli they did a lot better internally. I remeber him playing against Porto and Benfica and thinking his team wasnt that good, but he was safe and that goes a long way in tournments when you have good players. Then PSG came, he did what everyone couldn't, lose the league with that squad, and then he did go to Arsenal and I think he could do better at some times but would never be the type of manager Arsenal should go for.