What if Beane is downsizing the rotation?

I'm really stunned by the Mulder trade.  Not angry, not hurt, just completely surprised.  When I logged on it was about the last thing I thought I'd read.

I fully admit now that I probably have no idea what Beane is cooking up.  But given that the unbelievable has already taken place over the last few days, I'm going to float some irresponsible speculation, because it's more likely to be true than anything reasonable.

We've all been discussing the new Moneyball market inefficiency scheme.  And it's obvious that the market for starting pitching is just exploding.  I think Beane realizes that it's virtually impossible for the A's to compete in the open market for even decent starters in today's environment.

So here's the speculation: what if trading 2 of the Big 3, acquiring a bullpen full of relievers, and talking up Street and Garcia means that the A's are planning on converting to a 4-man rotation next year?  Here would be the justifications:

1. As Earl Weaver said, it's easier to find 4 good pitchers than to find 5.  It's also a hell of a lot cheaper.  You cut the cost of your rotation by probably 12-15% of the starters' payroll in one fell swoop.
2. The A's now have a lot of talented relievers:  Cruz, Calero, Dotel (for now), Street and Garcia waiting in the wings, Duke for long relief.  There's speculation that they'll move Byrnes and Bradford to SD for Payton and Otsuka.  That's a hell of a lot of potential quality bullpen innings.
3. The 5th starter is useless in the postseason.  It's very hard for a limited budget team to invest precious resources in a player who plays an important role during the regular season and then becomes totally irrelevant in the postseason.
3.  The 4-man requires healthy starters -- and guess what Beane has done:  he's traded the two guys who've been hurt every year and kept the one guy, Zito, who's been healthy.  One way to keep the starters healthy, of course, is to give them somewhat shorter outings.  Last year's bullpen was completely incapable of giving that kind of support to the starters.  The 2005 and 2006 bullpen is shaping up to be a different story.
4.  Now, I'm really reaching here, but Beane might also be seeing the BALCO revelations as a watershed in how baseball is played.  If you assume that (a) a pretty significant number of hitters are bulking up with steroids, and (b) a new testing regime will significantly reduce the number of players who use steroids, then (c) we might be on the verge of an end to the Dinger Era.  And the more we return to lighter hitting lineups, the less stress a starter faces in each start.  One of the reasons that pitchers used to be able to throw 300 innings a season was that hitters weren't as good (and ballparks were bigger, and bats were heavier, but I'll leave that for a different discussion).  Even when you were facing, say, the 1983 AL West Champion White Sox, who won the division by 20 games, you got to face the Jerry Dybzinski-Vance Law-Mike Squires-Julio Cruz part of the order (I checked, those guys were starters at their positions), and that didn't exactly make your starter work his hardest.  And the White Sox led the Major Leagues in runs scored that year.  These days, everyone hits homers and pitchers always have to bear down.  Beane might see this beginning to change, thus lightening the burden on the starters and making the 4-man a realistic plan again.  It also might explain our suspicious lack of a 40-HR guy in the lineup...