I would assume that in your mind, Ozil took straight over from Fabregas as best midfielder in the world. What's funny about that is that in your mind Arsenal had the best midfielder in the world for most of these years yet never won the league or a major European trophy. And in spite of that, you think the manager you had at that time was also a genius. I don't know how this all adds up, but you should probably have spent more time watching football teams other than Arsenal over the years.
Özil was not the best midfielder in the world at Arsenal for long, but he was in 2015-2016. At Real Madrid, he probably was the best for a year or two. The reason we did not win the biggest titles can be attributed to a few factors. We lacked powerful and tactically disciplined players in defence and defensive midfield after we moved to the Emirates and Vieira, Gilberto and Campbell left. These sorts of players are sometimes necessary to win titles. That is the main reason.
I also believe there was a prevalent bias against Arsenal from the FA. I've actually seen one of the indexes used to measure the effect of refs. Can’t remember where, but you can probably find it. From around 2005, Wenger was cost minimum 10-15 points a season by referees. That doesn't even consider dynamic effects like confidence. Internally, Arsenal knew of the factors going against him. He became stubborn and didn't buy powerful and tactically disciplined players. Wenger needed battlers in his side to get over this. They even manipulated fixture lists against his teams which is why the Invincibles just won the PL for example ( seriously, look that up). The players did even more than they should have all things considered. This anti-Arsenal bias started by Wenger calling out referees many times in interviews, and was made much worse by him saying ” Manchester United would be mid table if there was video reviews of refereeing calls” in 2005.
This sounds crazy, and I probably should not believe it, but I do because I want to.