In the early days of the Napoleonic Wars, Napoleon kept crushing army-after-army in part because he accurately valued artillery while almost everyone else undervalued artillery, so his army had more and better artillery than other armies.

In the early days of WWI, lots and lots of cavalry units got wiped out because no one realized that infantry weapons had vastly surpassed cavalry to the point of making them obsolete. Likewise, lots of smaller armies unexpectedly won defensive battles against huge attacking armies because most generals didn’t realize that defensive positioning had been massively buffed by machine guns, barbed wire, easy trench digging, and other technological innovations.

My understanding is that there has been at least one major unexpected paradigm shift revealed in the Russian invasion which has benefited Ukraine.

Anti-tank and ground-to-air weapons have proven super effective against tanks and planes. Or in other words, fairly small weapons that cost thousands of dollars wielded by a few individuals with moderate training have proven quite effective at destroying enormous machines that cost millions of dollars and are piloted by extremely well-trained soldiers.

Fortunately for Ukraine, Russia has tons of expensive tanks and planes, while Ukraine has been importing nice, new, shiny, almost state-of-the-art anti-tank and ground-to-air weapons from the West. This has negated two of Russia’s greatest military advantages and undermined the use of overwhelming heavy armor and air support as key strategic elements in the initial invasion.

While Russia’s strategic mishaps hindered its offensive, it’s important to note that Russian and Ukrainian forces are still at about parity. Russia has gotten badly beaten when it advances against Ukraine with even numbers, but we shouldn’t assume Ukraine will keep winning by such margins as Russia continues to consolidate its forces and slow its advance.

IMO, the Russian army has perversely become somewhat underrated, and vice versa for the Ukrainians. It seems like a lot of commenters are assuming that the Ukrainian forces will keep stonewalling Russia in the months ahead, but the shape of the war looks different now. Both sides have settled into lobbing artillery at each other and using small, incremental advances at strategic points. Russia seems to have learned its lesson and isn’t throwing away massive tank convoys anymore. We should expect the balance of military success to be more even now.