I'm firmly convinced that if you took an average chess-warrior and swapped him around, he'd notice no difference in the behaviour of his friendlies or his enemies.
Overall numbers actually mean very little. You know why? Because nobody from ANY side will engage when they don't have numbers.
So if the numbers are even, you'll see one horde of 15+ (knight, or rook, or bish) planes hitting a preferably undefended (bish, rook, or knight) field, while the next sector over there will be a similarly sized horde of (bish, rook, or knight) will be hitting a preferably undefended field of the (bish, rook, or knight).
If the numbers are vastly lopsided, you'll typically see 2 or 3 hordes instead of just one for the one team, but you'll still see the "outnumbered" team hitting back against an undefended field belonging either to the 3rd team or the "big" team.
One thing I've noticed, although this may be personal "bias", is that the rooks do seem to fly higher and more timidly than the bish or knights. Usually they are in the faster planes (runstang, la7, run90) and will make a couple bore n zoom passes and either run or orbit while calling for friends. This happens on all sides, but it seems to be the modus operandi for the majority of the rooks.