Blaming the december spell on injuries is shameful, considering the team you're talking about. That's no excuse. They lost against an open Chelsea and 2 proper canon fodder teams. If half a billion worth of depth doesn't cover that, what will?
And no, City have not undoubtedly been the best. The league table shows that. Just because City's shining a bit more highlights wise (loads of goals and pretty stuff) it doesn't automatically make them "undoubtedly better". Our defense has been excellent, on another level compared to City's and our CL campaign has been more memorable too (the wins against PSG and Napoli in the final match plus a very decent display against Bayern's bus). Also, our heights, against Arsenal or Utd have been masterclases, way better than anything City's shown.
If the season ended now, they'd be rightfull and deserved winners, but in no spectacular fashion. Newcastle, Shalke or Chelsea have recently shown they're as vulnerable and flawed as anyone.