Okay,
I'm starting to get the feeling that your repeated dismissal for Ukraine's abilities/equipment come from a lack of understanding on how important/capable the country actually was/is. To put it in simple perspective, Ukraine was more important to the USSR than Scotland is to the UK. They were the second biggest state and it was their leaving that gave Russia no choice but to dissolve what was left of the USSR.
More perspective, the reason Russia has sold/scrapped all but one of it's Soviet aircraft carriers is because they are Ukrainian carriers it inherited when the USSR dissolved and Russia lacks the expertise to correctly maintain/upgrade them. The reason more than half of Russia's Soviet tanks sit rusting in storage is because they are Ukrainian tanks and they lack the expertise/parts to maintain/upgrade them (all the best tanks were built in Ukraine, Russia just handled the budget T-72 model).
So no, they didn't use sticks to upgrade their S-300, or their Buks, or their T-64s, or their T-80s, they used the expertise and capability that came with having some of the brightest minds and best factories in the former USSR.
NB: I didn't realise until I checked how many T-64/T-80 Russia have rusting away that their active tank force is only on par with Ukraine's, I honestly expected them to have an advantage there, that will certainly make invading extremely difficult if they can't achieve air supremacy as they will be outnumbered as armour goes (as they aren't going to send every tank in Russia).
Well that hearsay came from the Wikipedia article you cited, but fine here you go:
https://www.asianmilitaryreview.com...incoming-missiles-at-less-than-10m-altitudes/
There's many more examples if you search for them, including Israel complaining that Russia are using Buks to shoot down missiles they fire into Syria.