With the Island terrain, if the CHog wasn't perked, I have little doubt it would be up to 25% of arena kills this tour. It's awfully convenient to skip Tour 15 in stats comparisons. And expect the Spit IX and Niki to be reduced quite a bit this tour, and the D-Hog, Hellcat, and Seafire to be up.
The increase in Spits, as best I can tell, for the last couple of tours is due to the massive influx of people from AW (where, I understand, the Spit IX is the uberplane) and is totally unrelated to the perking of aircraft recently.