Re: Baseball by the book:Plate Discipline
Pitchers who are wild actually maintain medium P/PA levels because they're leaving balls over the plate often enough to give up hits early in at bats and balance out their walks. Their high pitch count from from lots of PA, not from lots of pitchers per PA. Pitchers who have better control and miss lots of bats are the ones who have P/PA, but are successful by limiting their PA. The PA part of the equation is variable and has a very strong relationship with runs allowed.
Hitters meanwhile have a "fixed" number of PA. Thus, in any given at bat, getting more pitches can still tend to be a good thing. I love that line oneupper. I think Vlad is a great example. Getting a high P/PA isn't about getting a walk. It's about getting a good pitch to hit and walking if you don't get one. The "problem" with Adam Dunn is that he doesn't make enough contact so he often works himself in to a 2 strike count and then can't connect with the pitch he gets to hit. It's why a guy like Pujols or Sheffield sees a lot of pitches but doesn't strike out very much.
Good pitchers can go deeper in to a given AB without ever giving the hitter that pitch to hit (or make them miss the one they get), bad ones can't. So for pitchers, more pitchers per AB, but fewer ABs.
Games are won on run differential -- scoring more than your opponent. Runs are runs, scored or prevented they all count the same. Worry about scoring more and allowing fewer, not which positions contribute to which side of the equation or how "consistent" you are at your current level of performance.