
(k+d) (total) is being used as a rough indicator for plane usage (#of sorties was taken out of the stats shown a long time ago). k/d however, is strictly air-to-air only.

"domination index" - of course I made up that label myself. It's kills-deaths (air-to-air), and somewhat measures the impact a plane has on the arena in terms of air combat.
"But Yaks are EVERYWHERE, it's all you can see nowadays!?!"
No, they aren't. What planes you encounter can depend on a lot on what kind of battles you are fighting. For example to me, hunting buffs at med to high altitudes or defending bases against enemy assaults, Yak-3s are relatively rare. If you are the kind of chap who likes to slug it out with your friends in the weeds just between two bases, you will certainly see much more of them.