So basically give the yaks preferential treatment...
The in-game 109G/K are heads and shoulders above the (projected) Yaks in climb/range/firepower and raw horsepower... thus the ENY for 109s reflect that.
I really doubt a Yak-9D will be modeled so I think it's definite to conclude Yaks and pretty much the Soviet fighter lineup will remain short legged.
Heck, graph wise, the Yak-3 won't be that far from Yak-9U and the earlier Yaks will be no better than P-40s.
I use 109 as an example because it's the main fighter the Yaks tangled with.
We gotta start initially with an attractive ENY not only because of the shortcomings I pointed above, but to also to keep the plane fresh and interest going. if Yak's 3 and 9U's presence does increase then the ENY should be adjusted.