I don't agree with most people who use xFIP to say how a pitch actually pitched. xFIP crosses the line of talent measuring and goes into a full on ERA predictor once it manipulates HR allowed imo. FIP is probably the best measure of talent for what actually happened. I would use FIP.
I agree for the most part. I think people confuse "what can expected to happen in the future" with "what should have happened in the past." The ideal outcomes discussion is a discussion for a different day I supposed.
Again, I think people confuse the two. I think saying a pitcher did well when he struck out 8 and walked 2 but gave up 5 ER isn't correct, but it should be said that that pitcher is at least taking the steps toward being successful by some of his outcomes such as SO, BB, and so on, but again, for another day I guess.