A Ukrainian continuation of Rumsfeld's observation: "You fight with the army you have?"
Syrskyi represented the bulk of the Soviet trained army that Zelensky had.
Zaluzhny was not part of that Sovietized cadre. He was effective with Ukraine's new army but had no friends in its old army. He thought western.
While Syrskyi attempted to hold the line of contact adding new toys to old-school methods a guy name of Budanov, in Intelligence, was rewriting the rules with his new "reconnaissance" troops, his marines, his USVs, his UAVs and his campaigns in the Black Sea and in Russia.
Zaluzhny was sacrificed but Budanov was retained and is now Zelensky's right hand man as Head of the Office of the President of Ukraine.
My money is on Budanov being the architect behind the current advances and that both Syrskyi and Fedorov were expendable. I am willing to bet that Fedorov was working to implement Budanov's plan and the Syrskyi was digging his heels in.
en.wikipedia.org
en.wikipedia.org
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Meanwhile Syrskyi's replacement, as noted by
@HavokFour , seems to be more of a "cavalry" soldier, even if he is a para. He seems like he might be less risk averse and more offensively inclined. And more open to reforms.