Ok, I tend to be a big believer in Pitching and Defense wins. While I accept balance is always prefered, if you can only be strong in one area, pitching is the best area to be strong in. For example this is why Texas is always stuggling and Atlanta is always winning.
But I did some checking going on the assumption (just so you know the bias approach I am taking) that the winner of each division and the Wildcard is probably the best team ERA of that group, with some variance given to hitting, if the pitching is really close.
I had a more detailed write-up but accidentally deleted it, and was too lazy to retype it all, so I will give a summary:
The only abormalities from 2002-2005 (4 years) was Toronto not being in the playoffs last year (as AL East Champion or Wild Card), The Twins and Marlins in 2003 (Looks like it should have been White Sox and Astros).
In every other case the team with either the best ERA, or almost best ERA and a much better offense won either the Division or the best of the rest race.
Results, prove, if you have the best pitching in your area (divisional or Wild Card race) you will win (most of the time), but scoring runs will help seperate those teams that are close in pitching, and sometimes FLUKEs do happen but not often.
Quick and dirty numbers:
2002:
AL East: Yankees (close 2nd, but beat Bos in Runs Scored)
AL Central: Twins (1st)
AL West: A's (1st)
AL WC: Angels (1st)
NL East: Braves (1st)
NL Central: Turdnals (1st)
NL West: D-Backs (3rd, but best in Runs Scored)
NL WC: Giants (1st)
2003:
AL East: Yankees (1st)
AL Central: Twins (3rd, Aboration?)
AL West: A's (1st)
AL WC: Red Sox (8th, Aboration?)
NL East: Braves (1st)
NL Central: sCrubs (1st)
NL West: Giants (2nd, Dodgers best in ERA, Worst in Runs)
NL WC: Marlins (6th, offense the difference)
2004:
AL East: Yankees (2nd, Curse is only explaination here)
AL Central: Twins (1st)
AL West: Angles (close 2nd, Runs difference)
AL WC: Red Sox (3rd, barely behind As and Twins)
NL East: Braves (1st)
NL Central: Turdnals (1st)
NL West: Dodgers (1st)
NL WC: Astros (6th, Cubs collapse, magical 2nd half)
2005:
AL East: Yankees (distant 2nd)
AL Central: White Sox (1st, tied)
AL West: Angels (1st)
AL WC: Red Sox (11th, WOW, FLUKE!)
NL East: Braves (3rd, but very close to 1st)
NL Central: Turdnals (1st)
NL West: Padres (1st)
NL WC: Astros (2nd in ML)