ESS swap with z-targeting

I was playing around with ESS swapping, and found that if I Z-target a couple of times I get the same result as swapping the ESS position, but without having to move the control stick. I have no real idea how it works though, can anyone explain?

Thanks

This happens if you slightly hold straight down for ESS. Basically what happens then is sometimes when you change Z-target you change his sideroll angle which makes the ESS swap.

Also next time please post questions in the Question & Answer topic: http://forums.zeldaspeedruns.com/index.php?topic=26.0