Many things were quite obviously amiss. Do you genuinely believe the club/mgmt have not been thoroughly reviewing them since mid-season? I think the levels of assumption in your post here are large. The whole 'ankle/upper body'? I mean, that's obvious. What are you saying? The whole 'watching and gauging while injured'? Again, what are you saying?
Injuries are only part of it. Rhythm on return, constant shuffling, fatigue affecting focus, there are so many factors. Inflexibility through January might well have been another. Essentially you either trust Postecoglu and the club to have seen the story and be planning changes to make sure none of it happens again, or you don't. You either believe there's a rare ether which comes with winning together in adversity -and want to buy into that- or you don't.