[NoOne]

this is all real as shown be very basic math and a few facts we know or can observe in game without a spreadsheet or a calculator (just an eyeball).

they are more liekly to get hurt when pitchign tired, that's for sure true..
they don't pitch as well when tired -- defintieyl true
it costs more for 1 pitch after 'tired' than before that point relative to how much they can throw in the next game. it is not an equal cost.

so, avoiding it will help for sure. maybe not a full 1.00era less, though.

one other note about starting highest rested -- this is where a pitch count helps a lot. ~80% won't happen with a good pitch count. maximizing GS results in more IP then pitchign tired in a few games and the resulting loss of pitches or delayed start in their next spot in rotation due to being <100%.

the percentage fatigue you lose (or gain depending on perspective) per pitch after "tired" is not equal to the first ~100 or so pitches... therefore, you can throw more in a season when you avoid a pitcher throwing when tired.

e.g. let's say it is +10 (totally made up, use "x") pitches beyond "slightly tired" where that pitcher will be ~82% by their next regular day in rotation. they lose MORE than 10pitches relative to how many it takes to get to "tired" in that start. i.e. they can throw fewer times in same # of GS and at a lower ability when tired, remember too.

this is most easily seen with a high-end KB pitcher, because they are more consistent at staying in a game long enouhg that pitch count is often enough that pitch count is used neaerly every start.

i can get ~280ip with no pitch counts, but i can get 2 extra GS and ~300ip when i use a pitch count. mileage may vary (i have custom 6on1off schedule for example) but what cannot change is the dynamic...the math stays the same. 1 way costs more. it is not 6 in one half dozen in the other.

it costs more stamina/fatigue to pithc tired, therefore if you pitch tired in a lot of starts you will throw fewer innings over a season. and, a larger portion of those pitches will be thrown when tired and at a lower ability than normal for that pitcher... quantitatively worse.

Strict order -- not as important when there is a day off - removing it for 1 GS is always an option... it doesn't have to be the same pitch count every game.

without a day off, you have no option to substitute that ~80% SP excluding a AAA call-up, which also may have fatigue issues by chance, if last second decision like this.

1 other factor could make it unimportant to a large degree... this will assume 5-man rotation - 2 SP fatigue settings work for a 5-man rotation... if you see the high stamina guys "ready" 1 day early, it's not the same setting as i am using and some things that i say need to be amended based on those differences.

low and very low? i can't recall the syntax. 1 allows for the high-stamina SP guys to pitch on 3 days off instead of 4 days off. all the concepts would apply, but 1 less day for those guys etc... you could get more starts under that 'other' setting for sure on these guys... (1/4 of 162)=GS > (1/5*162) not counting days off that help..7 or 8 more starts in that situation will guarantee more IP than ekeing out a few tired innings over the course of a season.. and better results (quantitatively true due to pitchign tired being a negative effect and minimizing such behaviour)

either way, paying attnetion to pitch counts and their effect on the next start can most defintieyl improve your results. it's undeniable in OotP. to argue with it is to argue with what basic math tells us to be true and not some opinion or feeling.