I think that's a skill issue. Ukrainians are operating similar equipment with better success. Much like how India and China seem to have no problems operating the sister ships of the kuznetsov
Air defence was a weak point for Ukraine until Western countries provided some. As for the S-400, it's a post-Soviet design, and if the T-14 is vaporware and the Su-57 overhyped at best, perhaps one should not take claims on the S-400's capabilities at face value, especially given that there is visually confirmed evidence for two of them having been destroyed.
Not really. Ukraine had perhaps the most comprehensive ground based air defense network in Europe apart from Russia by virtue of the sheer quantity of S300 batteries.
The problem they faced last winter was that they were finally starting to run low on missiles and that using S300 on $20,000 drones was incredibly wasteful.
The only capability they were really missing as opposed to just running short on was the anti ballistic missile capabilities.
