Which makes sense because preventing a run and scoring a run are equally valuable. Also, defense is added in to pitcher’s WAR value, just the same as for position players. I’m not sure how good of a job UZR (fWAR) or TotalZone (rWAR) do for measuring pitcher fielding, but it’s in there.

But there is another, completely separate issue that comes in to play for pitcher WAR, which is whether you use something like ERA, which includes contributions from the defense, or FIP, which is defense independent. Baseball-reference (rWAR) does the first thing and fangraphs (fWAR) does the second. This is why pitcher WAR values can vary a lot between those two sources. For more explanation of this issue, see Why Our Pitcher WAR Uses FIP and Why Our Pitcher WAR Uses FIP, Part 2

Relief pitchers are a whole other can of worms because you might want to take into account the high leverage situations that they pitch in, but then you also need to take reliever chaining into account (like if your closer is hurt, then you don’t give those high leverage innings to some scrub from AAA, you use the next best reliever in the bullpen).