I just re-read Moneyball this weekend, ten years after I first read it-- it's amazing to look at the people that the Oakland A's were considering (and coveting) as minor league prospects 10 years ago, and to see just how many of these players have panned out as MLB stars-- Youkilis and Swisher for example-- and others became serviceable big leaguers (Joe Blanton, Teahen)-- so my question is: Has the "Moneyball" (or call it the Sabermetrics/Bill James) approach to evaluating and drafting players been validated or debunked?

I know that Billy Beane follower, Theo Epstein, managed to bring two World Series Champs to Boston after 86 years of waiting (but Beane and Moneyballers always contended that post-season success is not something he/they can guarantee-- it's too much about luck, and Boston never ceded the monetary advantage that they had over everyone but the Yankees, so it's possible that Epstein's success is not necessarily any validation of Beane's approach), but J.P. Ricciardi hasn't done anything in Toronto worth noting, and I don't see the Mets doing much under Beane protege, DePodesta, and even Oakland has fallen off from their late '90's- early 2000's run... so is there enough evidence to support the validity of the Sabermetric approach to building a baseball team? Have all teams adopted the approach, to some degree (in other words, victory of the theory, without acknowledgement), or are teams building winners in nearly complete ignorance of Sabermetric principles?

I have not heard anyone say that the Cardinals (who also have 2 championships in the last 10 years, along with another World Series appearance) are a Sabermetric-oriented team-- and I certainly doubt that Tony LaRussa would acknowledge managing that way-- he's about as "old school" as they get, I'd imagine... and the Reds have started to get good finally (after 10 years in the wilderness), by essentially re-applying the Cardinals' master plan (the Reds have a former Cardinal co-owner and former Cardinal GM, who built their championship teams), and the Cardinals/Reds MO seems to be an emphasis on building up scouting strength (of the old-school variety) rather than statistical analysis.

So, to be more specific: Has it been demonstrably proven that On-Base Percentage is the single most important offensive stat in baseball? And if OBP and Slugging Percentage are the two most important stats, is OBP really three times more important than Slugging Percentage? Is pitches seen/drawn really the most important underlying offensive statistic? Is it true that the only thing that matters for pitchers is their ratio of Strikeouts, Walks, and Home Runs Allowed to batters faced?