That has been an Arsenal problem in general. They've had squads that should have been good enough to win titles in the past but barely muster a challenge. We've managed as many genuine title challenges as Arsenal have in recent times despite having weaker squads for the most part. Non factor in the Champions League for a decade.
I'd be delighted if they lost Ozil.
I've got to disagree with you slightly, in the past we've had glaring weaknesses in our team, never mind our squad, in comparison to our rivals anyway that has stopped us truly challenging. In the early part of this barren run we had guys such as Almunia, Denilson, Senderos, Eboue, Bendtner etc getting way too much game time. Perhaps on paper if all the players remained fit we could have challenged better, but we lost guys like Vermaelen, Diaby, Ramsey, Rosicky, Eduardo, lately Wilshere all out for over a year, nearly all have never came back the same player, & Van Persie managed 1 season largely uninjured.
I'm not saying your squad was any better when you guys challenged, but a title challenge is made up of a few different factors, 1 of them is being able to field a full strength team over a period of time & getting results which helps build up momentum. The 2nd thing which really helps is having a few top class attacking players at the top of their game for a decent stretch winning matches for the team (Hazard - Costa, Vardy - Mahrez, Sturridge - Suarez, Gerrard - Torres, Silva - Aguero just a few examples. We've never had both of these, certainly at the same time.
I'm not saying we're just unlucky, blameless etc because obviously we should have managed the situation better, especially in being too loyal to injury prone players & not replacing them well / quick enough. Only in the last couple of years i feel as a fan the squad was getting close to being good enough. There were still weaknesses in the team up until this summer that weren't addressed (a proper partner for Koscielny, a top class physical midfielder, a top class striker), the jury is still out whether these have even been addressed correctly.