This is an unbelievable game plan. 12 pitches, 12 sliders. It’s not like he’s a one trick pony, the fastball also grades as an excellent pitch with obviously elite velo.
To be fair his regular season load is not that egregious for a reliever. Jeff Hoffman for instance pitched 6 more innings and got into 7 more games. Not sure if keeping his usage low in the regular season was on purpose but he should be pretty fresh all things considered.
Kirby’s numbers are historically MUCH worse a third time through the lineup. At that point you’re risking the game getting out of hand by leaving him out there. Just because the reliever coming in blew it doesn’t mean it wasn’t the right move to make. The odds of that homer happening are much lower than one of the other guys beating Kirby.
At 99 pitches I don’t think there’s any chance he’s not coming back out. Only question really is if you let him finish the inning at 115-120 pitches. I say the answer is still yes. I only consider taking him out if he allows a base runner around the 115th pitch.