Years ago when I was a kid teachers tried to tell us how a command economy just didn't work. That article certainly gives the impression that the Russian military is still stuck in the same mold as the old command economy of the Soviet Union. I hope what he said is true.
More importantly, the Russian army is stuck in a deepshit loop of corruption and abuse.
If a huge part of your potential soldiers pay several month-incomes to not get into the army (before the war), it tells you all you need to know about morale. The soldiers still in there are so poor they steal washing machines after all.
If equipment does not even start because generals have pocketed years of maintenance, it tells you all you need to know about reliability.
Having a big army that is not good at fighting (against another army) is normal in a dictatorship, not least because a competent army is a thread to the leader. But the Russians have a big load of past bad baggage with them too.
On the other side the Ukrainians may lack in equipment, but what they have works and their morale is sky high, with a competent leadership who is not in there just for grabs.
That is the base for the saying that a dictatorship never wins against a democracy. It's wrong, they often do, but they generally lose if the fight is not over in the first attack, because they can't really increase their fighting power (it risks their leader's survivial) while democracies will double down as much as needed.
Read the book in my sig, it's there for a reason.