Each club has a registered squad of 25 players.
At any given time, the Manager/Coach and his backroom team SHOULD have a handle on the fitness of each of those 25.
It is accepted that all of the 25 are not of an equal ability. Each Manager/Coach therefore has to operate within that constraint, taking into account also the differing abilities and playing positions of those in the squad.
This is a 100% 'red herring': '...a combination of fixtures, the return from Covid break & effectively extended season...' We are talking here about sportsmen at the highest position of their calling. They are the fittest of the fit, and had a 3 month break, longer than the normal summer break. They are asked to play (sometimes) twice a week.
The whingeing and crying of some Managers (you know who) just doesn't wash with me. Don't cry wolf when you run your players into the ground...
Firstly - completely in agreement with you on the whinging and cryarsing of you know who & ultimitely that has come back to bite him with others digging their heels, but your arguement of they have 25 players just rotate them doesn't wash.
The study that showed the 42% increase in soft tissue injuries also showed that, due to covid, no preseason and the rolling nature of last season into this, that the likelyhood of picking up an in-game soft tissue injury doesn't correlate with being rested the week before. Yes, it reduces the odds, but only slightly. It's about the fitness miles in preseason, the rested bodies etc; not simply rotating game to game.
If rotation was the solution, why would the "big six" be the most vocal here; they have the most rotatable squads.