Yeah your numbers are totally wrong. Allow me to elucidate. The pivot occurs at a stamina that is 40% of your current max stamina (not starting stamina). At 40% your recovery behaves exactly as before. Below that you recover slightly faster with the bonus increasing until it reaches a 20% buff at zero stamina. Above 40% your recovery is slowed down slightly with the debuff to recovery increasing to a 30% decrease to recovery when you are full stamina.
Mathematically this works out to an overall debuff to stamina recovery with the only people getting buffed being those that live at under 40% of their max. The idea being that newer players spend more time in that range and are already punishing themselves because strikes in this range hit your max stamina so much more often.
As I have often said balancing between having an accessible game for new players and a good stamina meta for experienced players is a tough nut to crack. I hope this gets us one step closer.