I guess I don’t understand why a pitcher’s teams offenses effects his pitching ability? They have no control over that. The way to remove that from the stats is easy…ignore W/L record.
FIP only counts those things a pitcher can control (walks, strikeouts, home runs) and tries to ignore those it can’t (non-HR batted balls), but you are right that it’s hard to completely remove every variable from baseball. No stat is perfect.
Baseball is a funny game. If there’s a runner on third with 1 out and the hitter flies out to CF, he has succeeded. Same situation, except with two outs, and he’s failed.