I think one of the hardest things to try and do with stats is compare one fighter or ace vs another in WW2. There are many reasons, the foremost is that the fortunes of both sides could change dramatically in the space of a few months, or years.
Look at the ETO. The 8th AF fortunes went from a low point in the Schweinfurt raids in August 1943 to a high point in the spring of 1944. Thats @9 months. In that time you have P-38 groups re-entering the bomber escort role after the N. African campaign interlude, and you have the first P-51Bs entering service. P-47 groups continue to fly escort missions as well. The # of USAAF grps are also getting larger as that time moves on. Every air combat mission is different, the fortunes of one group is not the same as another. In addition many of the missions the FGs flew were a combined effort, with mixed types. There are so many variables to look at.
I draw that one example as an illustration, but the same can be applied to almost every theater in WW2. A lot can change in 9 short months, good and bad.
For all the debates about the BoB, I have seen so many posters act like the Spitfire, Hurricane and 109 and 110 all flew in a vacuum where all they did was duel each other 1 vs 1. Regardless of your opinion, you cannot divorce the types debated with the missions they flew, or pretend that they alone were responsible for their fate. Fighters did not fly in the BoB all by themselves, nor did they face just one opposing type, or unit.
Brewster Buffalo. Do you judge it on how it did in the Dutch East Indies in 1942, or in the Finnish-Russian War? "Well that all depends"..., yup.
Im not saying you cant take a hard look and try to draw some conclusions, but its hard to do just from comparing raw stats.
