AgLA06 said:
Their numbers were originally thought to be high and propaganda. However, multiple sources have analyzed them. Based on visually confirmed losses (which will always be conservative) they seem plausible. Even the western intelligence numbers which purposely err on the low side weren't much different. Intercepted Russian conversations seem to reinforce extremely heavy losses and a Russian wounded to dead ratio closer to WWI numbers than modern warfare expectations.
I think a lot of those numbers are at least in the ballpark. However there just isn't that much evidence of aircraft getting shot down to match those numbers and there's lots of incentive to document those losses. Numbers of aircraft shot down is something that has been notoriously greatly exaggerated by many countries through many conflicts.