True but without radar they have a relatively difficult task of being out there setup and waiting for a fast moving jet to pass within range.
Compare that to Ukraine defending it's skies with NATO (well mostly French IIRC) AWACS feeding early data which is what made MANPADS in Ukraine so effective against Russian attacks.
Yeah my guess was they were coming in along predictable routes at this point and that's what got them? I saw that the search and rescue mission was in an area close to water. I believe many Stinger hits in Ukraine can be attributed to predictability.