It's a multitude of factors
The arsenal don't like getting kicked mentality leading to contact injuries we can't do anything about.
Injury prone players
Injuries spiked when Lewin left and we put his son in charge instead of find the best physio available
Developing young players always pick up injuries adapting to the demands of senior football.
Playing fatigued players "in the red"
Poor injury prevention programs
Over training players when there fatigued
Poor late stage rehab / early return to play
I'm not saying we have all these things but we must have a couple. It's not just the physio or the medical team, managers can play players into the ground or the s&c coaches can train players badly/ to hard before games leading to accumulated fatigue and injury.
The manager needs results so will risk some tired players.
The fitness coaches have to maintain the plays conditioning so there trying to train them as hard as possible without going overboard and picking up overuse injuries. It's a knife edge.
The physios have to design injury prevention programs, the more previous injuries a player has the less effective these programs become. As your trying to fix " tracking" the brain is constantly adapting " tracking" around previous injuries. So when jack or Ramsey has these history of injuries there harder to keep injury free.
It's a group effort and evenone will blame everyone else.
In the US the fitness coaches get fired first in the UK were quicker to blame the physio.