Well, that's playing down your potential problems in goal-scoring dept. a bit, don't you think?
Our top scorer is Sadio Mane, and he scored 17% of our goals. Meanwhile, Ibrahimovic scored 41% of United's goals.
And the actual top four teams? Outside of Chelsea with Costa (33), none come close in hardcore reliance on one player that Manchester United have right now. Not to mention, the actual top four teams have all scored around 40-45 goals, you lot didn't even score 30. And before you say, "well at least our defense is solid", I must quickly point out that we've got the same number of clean sheets (6).
All that combined with the fact this is by far the most competitive PL season ever, with Spurs in fifth with 39 points (previously unheard of), as well as Kane not even in his final form yet, United fans must ask themselves whether or not top four is even a realistic goal this season?
In my honest opinion, without significantly strengthening in the striker/winger dept. in January, it's probably not.
Your "better depth than rivals" this season is essentially "more famous players than rivals", results just don't cut it. Perhaps with Mkhitaryan finally fit, this will change, but outside of City, nobody is currently failing, and City will be replaced by Spurs in fourth. I'll admit Spurs lack mental strength to see out a competitive season, but that's also the only argument you still got on why you should be in the race. Well, that and obviously City falling on hard times.
One could say that CL distraction will hurt three of the top teams, but then again you have to play EL, so not much good news for your fitness coaches there either.