The root cause of the multiple injuries are probably too many games with too little recovery time in between - and FIFA/UEFA's ludicrous increase in international tournament sizes in recent years turning football into a year round activity with insufficient time for pre-season (so players start the season less fit than they should be)
ATM we are playing weekend-midweek- weekend which gives recovery times between games of 3 or 4 days - and I've read elsewhere a number of medics/physios saying that with our players running 10 kms or more each game ideally they should be having a minimum of 4 days between matches and rotated so that they are not playing every game.
And if you get a few injuries it restricts the opportunity for rotation and increases the probability of the fit players picking up injuries.
We started off the season with a squad that was full in terms of EL squad rules (ie no more players that could be included - and hence no room for Spence to be included) but within that squad we had Richarlison and Odobert who became injured very quickly, Bergvall who initially was not experienced to play much (although he's looking much better half way through the season) with the squad having the limited reinforcement by the inclusion of youngsters Mikey Moore and Will Lankshear who can play a few games each.
But fundamentally our squad was relatively thin, and vulnerable to under performing or inconsistent players (and I would argue that Bissouma and Bentancur are both in that category), Son's decline in being able to play twice a week at a high level has been very sudden, and a few unusual events such as Vicario getting injured, Bentancur's 7 match suspension and it all affects the real depth of the squad
So I'm not sure that either Ange's coaching regime or medic's are entirely to blame, there a lot of luck involved too, and some players are better suited naturally to playing every 3 days - but I'd certainly be blaming FIFA/UEFA who are currently being sued by international players union for their increase in international match commitments.