it's kinda down to the acceleration you can develop at the start of a move that dictates how easy/hard it will be (excluding rider skill).
shorter chainstays means the bike is faster to get to the rear wheel which is good for hops, higher bb makes the bike more unstable, but that instability means the bike can change direction very quickly which is good for spins.
Think of the Eurofighter jet, that is designed to be very unstable in the air and needs computers to keep it flying, but it is VERY nimble and can change direction faster than any other fighter, this translates to bike frames too. Obviously you can go too far and make the bike ride more nervously than a geko in a microwave though!
It still amuses me looking at "street" mtb frames with bbs dragging on the floor and chainstays a mile long.