Well for starters they won four division titles from 2000-2006 and won the most games in all of major league baseball despite having one of the smallest payrolls in baseball. Most good teams now use the deficiencies in the market that Beane used to win all those games to win their games now. OBP is big now literally because if Beane and moneyball.
Ok this I where I think it goes off the trail a little bit. IMO the A's outstanding run had more to do with the Atheltics having the great luck of having a dominant pitching staff featuring guys like Zito, Mulder, Hudson, Harden, etc. The A's early 00's success IMO had more to do with their ERA and than with team OBP.
I don't think it's any coincidence that since those pitchers have left the A's have been average at best.
Also for many of those teams the "OBP" argument was overrated. As soon as mashers like Miggy Tejada, Giambi, Dye, Frank Thomas, Swisher left town and Eric Chavez fell off the team fell back to being average at best as well. The whole Oakland A's story is cute and nice as far as OBP go but the reality has more to do with the fact the A's had some really great front line starting pitching and got a hold of some prospects and veterens that could slam long balls for a few seasons before they either left for bigger contracts, got old and/or started to decline.
I think OBP is a very important stat but propping up the A's success around such a stat or an idea is misleading if you look at what the team had pitching wise and power wise. The A's didn't find some magical formula. They basically reworked the early 90's Braves idea. Trot out 3 or 4 really damn good starters. Have some guys that can mash HR's, add in a few glue guys, and make the playoffs and give yourself a shot.
Starting pitching and sluggers>>OBP in terms of importance to the 2000-2006 Oakland A's.