I tend to agree with you about the importance of starting pitching.  I have very few "bad rotation" teams that advance very far in the playoffs (though I keep trying).  But I have a lot of "bad" teams (a subjective term, I realize) that do well in the postseason with two stud pitchers and an otherwise undistinguished roster if I can somehow coax 88-92 wins out of them in the regular season.

I have one of those teams right now (Joss/Brown and a whole lotta nuthin') in the 3rd round of the TOC.  I'm convinced that a lot of the complaints from 110-win teams that get blown out in the first or second round of the playoffs by teams that were barely .500 in the regular season are cases of teams that paid disproportionately for two aces blowing past teams that "better" distributed their wealth.  If you have Joss/Brown, Walsh/Johnson,  Walsh/Alexander, Joss/Taylor, Walsh/Maddux, Joss/Pedro, etc. in the playoffs, your chances are about as good as anyone else's.

Having said that, my "worst" rotation to win a WS was a nine-starter monstrosity that included two Pattersons, Bill Burns, Schoolboy Rowe, C.C. Sabathia, Fred Toney and a few other guys whose names I forget.  Nobody really bad, but nobody particularly good except Toney.  The rotation took a lot of work to keep up.  I usually don't like to go "below" one of the Summers as my 3rd starter in terms of quality.  I think I won once with Joss `07, Tully Sparks and Fred Glade, and I lost the championship in 7 with Joss `07, Frank Owen and Amy's beloved Jim Scott.  I also won once with a 3-man rotation that had Joss `07, Nick Altrock and someone even more undistinguished.