The CHog was perked because HTC felt it was dominating the arena. The metrics (kills in a tour) were backing this up because this one plane had twice as many kills as the second plane, and this one plane was accounting for nearly 20% of kills (I can't remember overall or just fighter to fighter) in a tour. HTC felt that was too much usage for one plane, so they put a light perk on it.
The La7, N1K2 and Spitfires (any one model) taken individually do not dominate the arena like the one F4U-1C did. Instead of having ONE plane dominating the arena, you've got 3. Even then that's not really the case. The P-51D does a fair share of the killings in the arena.
Basically, the CHog was no perked on the plane's real life performance, but based on its usage in the MA.
