if anyone missed...
here interesting post about soviet fighters in 42-43 from one of authors of
this book (i'm not advise or PR, just, apparently, it's new info from archives)...
old sources have really have many little errors, understatements etc (for example, if i'm not mistaken, "yak-9 1942" began to fight only in kuban'43), so, if this is really more realistic picture of technical equipment of VVS in battle of stalingrad, it's answer, i think, why USSR could not win till 43...
experienced luftwaffe on bf 109f-4 and g-2, maybe, best german fighters according to complex characteristics, etc, against all these yaks/laggs'41-42, and, mainly, first series of la-5 with gargrot and 5 fuel tanks, low? level of command until the mid-end'43, some problems with quality (of planes, engines, weapons) etc...
it's really hard situation...