A LOT of the service record of a type depends on the experience level of the initial pilots (who pass on their opinions of the planes to the next pilots) as well as the quality of both the opposition's pilots and planes. In Finnish service, their best pilots flew the Buffalo against Soviet pilots who had zero combat experience and almost no training other than basic training and Soviet squadron service. Soviet pilots were discouraged from being inventive and were expected to fly "by the book." Bend a bird, go to Siberia. They were shot out of the sky in droves by both the Finns and the Germans.
A Soviet pilot flying an I-16 in 1939 - 1940 was a FAR cry from a Soviet combat veteran flying an La-5 / Yak-3/9 in 1944 - 1945. The Soviet pilots were nothing in 1939, but a German pilot found it very hard to survive in a Soviet sky in late 1944 / 1945. How many Finnish victories came after mid-1944? A VERY few, but their tactics and pilots were top notch.
It took some combat losses to teach the surviving Soviet pilots about combat, much as the initial US pilots were "green" and suffered initially against the Germans, who were combat veterans.
The Buffalo design was not very expandable to make it better, and the P-36 was. There may have been little to choose between them in 1939 - 1940 but, by late 1943, the basic Hawk airframe was very much the better airplane. Despite that, I'd take another plane in late 1943 if I were there and had a choice.