Well, if we look at this season, he did rest VDV, Romero and Udogie for all the early cup fixtures; so, any accusation that they were overplayed is unfounded.
Quite simply, if as a coach the backup players you are given by the club are young and inexperienced (Bergvall, Gray, Spence, Odobert, Moore, Sarr, Dragusin, Tel, Kinsky) or are just plan crap (Werner, Regguilon, Bissouma) then it makes rotation of the squad difficult - because you are far more likely not to get a decent performance. Senior players such as Davies and Son are showing their age and Bentancur and Richarlison both coming off a very injuries that could have been career ending.
The club needs to furnish Ange (or whomever our next coach is) with a BALANCED squad. The team on the pitch needs to have the right level of experience and ability no matter what rotation we have.
Any coach in world football with the squad and injuries we have had this season would be sitting in the bottom half of the table. The question you have to really ask :
1. How many of those coaches would have thrown their toys out the pram, lambasted the owner and sulked (e.g. Jose, Conte, Poch)
2. How many of those coaches would have sacrificed their own job to get the bare bones team into a European final.