[NoOne]

i think you got it from the second post but i don't think anyone specifically pointed it out.

its not percent. it's just pitch count. they can go upto roughly ~10 pitches over what you type in there. it is not 100% rigid in nature. they may even occasionally go more than 10 over. if i recall, but it isn't common, if so.

modern pitching stamina:
it's useful if you want to run your top 1-2-or even 3rd pitcher out there as much as possible and 4-5 get less starts. you can make certain that they are never below ~95% Rested, your choice on threshold, pitching on 1 less day of rest.

i'd also use it for crappy pitchers... if they get through 100 pitches with a good day, i will consider that a win-win and get them out of there asap.

to give an idea about counts:
70's / 100 stamina i do ~106-110 pitches and they can be ready with 1 less day of rest. you can go higher, but then you will see more often that the pitcher is too tired to send out with 1 less day of rest.

avoid high leverage is even better than "use less often" for middle relievers, if you don't want them in games where the score is close. i use "high leverage" as a secondary for cl, su and anyone else that can pitch consistently well in my pen - usually not more than 3-4 players with it. the guys that can have multiple years with an ERA in the 2.00's or very consistently in the low 3.00's i am willing to use them in high-leverage situations. if you have a serious gap between your top X relievers that might be enough reason to assign it to someone not quite that good. you essentially say i want this crappy reliever not this one... because you liek his pitch selection better or whatever but the AI would likely play the other guy first due to overall rating.

both of these options can help you keep the right people on the field when you want them there... if you play out every game, neither of these two options are very important to you.