I think a lot of the difficulty with talking about a yoyos performance stems from the fact that there is not a lot of quantifiable data once the yoyo is in motion.
It’s not like you could say this yoyo is a 5.21 on the Gentry stability scale.
I haven’t played a prescription in a while, but maybe he means stable in comparison to some of his other yoyos.
I consider my Top Deck to be a stable yoyo, but it’s less stable than my Horizon.
So, without a specific comparison, it becomes difficult to label something as stable or not stable.