With your way of thinking, one could fault coaches for underperformance, but they... are not to be credited for their successes? Was it not at least in part due to Mazzanti that Italy was regarded as a favourite (clear is arguably too strong a word, but they were favourite #1, no questions). Was he not Italy's coach for ECH 2021 and 2022 VNL (and before that, WCH 2018).
What about the player's own part in failures? Are you aware of numerous rumours concerning Pietrini (of her lack of 100% commitment to volleyball and fulfilling her potential, of her fragile psychological makeup, weird choices like not wanting to wear kneepads etc.)? Are you aware of the rumours that the entire NT was for years split into two camps due to a lover's quarrel, pro-Folie and pro-Pietrini, and that Sylla and Pietrini (who were often on the court together) would simple refuse to acknowledge each other's presence due to Sylla being Folie's bestie. That you couldn't substitute Egonu or she would get offended and sulk.
Even if most of those are unture, to paraphrase a common saying: "Where there's lots of smoke, there's bound to be at least a little of fire". And would you lay the entire blame for all of it on Mazzanti's door? Players have no agency? No choices in their own actions?
As Guidetti once said: "Failures should be attributed to the coach and successes to the players". If Mazzanti isnt able to porperly manage a team that might or might have internal problems then he's simply not suited for the job.
Do you think Italy was or is the only team with internal affairs among players?
Did you even know that the legendary Cuban team had even worse problems among their team member and yet they managed to conquer the volleyball world for almost a decade? Same with the legendary Brazilian team.
The rummors about team Egonu or Bosetti, egos, quarrels, etc. have been there for years and yet Italy has been able to show that when at peak they are clear favourites (even your ex NT coach has said it), they don't suddenly go away when they win but reappear when they loose.
