RUSI 연구원이 쓴 글인데, 결론적으로 숙련된 SAM 요원들이 전사하고 비숙련 요원들이 많아서 멀쩡한 러시아군 SA-11이 느린 무인기에게 당하는 것이라고 하네요. 같은 SA-11 계열이지만 좀 더 낡은 우크라이나군 SA-11은 무인기들 잘 잡고 있다고...
If you have expert crews then Russian weapons systems are highly effective and can be more effective in some cases than NATO counterparts. If you watch old Finnish or Ukrainian Buk operators who have been at it a while it is impressive.
But if you have short term contract soldiers - and especially if you lost a lot of your more skilled personnel early - then the Russians are left with crews whose basic proficiency isn't sufficient. You end up with less and less skilled people using the equipment.
That is how you end up with Russian air defence systems getting hit by UAVs. It isn't that a Buk can't see or engage it. The Ukrainians Buks which are less capable platforms are detecting and engaging UAVs just fine.
https://twitter.com/Jack_Watling/status/1553745899871952897