Consider these two axioms:
1) The main tactical evolution of the past 20 years has not been possession-based short passing, nor the eradication of free roles (libero, second striker) in favour of positional specialists (defensive mids, playmakers), but the way teams press as a unit off the ball.
2) A modern footballer performs double the amount of high-intensity sprints during a game compared to the 90s.
The main takeaway is that modern football breaks players, not through an added number of minutes (they play less today than they did 20 years ago due to increased squad sizes) but through higher athletic demands. Which means those big talents who are injury prone to begin with have no hope to make a serious mark in the game nowadays (like Isak or Schick). And many of those who aren't injury prone will break down eventually anyway because they play virtually all the minutes (like Saka).
What you're left with is a very small group of players in the world who are elite genetic specimen with a good injury fortune during their formative years, and they will play 600-800 games in a career without picking up any significant injuries. Find the best of those guys and build the spine around them. The others you have to cycle through every 3-4 years. Sacking doctors is just rearranging the deck chairs on Titanic in the final analysis. I doubt it has any impact whatsoever unless you've hired a particularly incompetent person.