It wasn't Jim's theory back in 2003 when I looked at how much scoring 
offenses can influence playoff outcomes (as opposed to the influence 
of pitching).  Back then, if you had scored more runs during the regular 
season than your playoff opponent, you had a .571winning percentage.  That 
percentage, through 2008, is up to .632 ... looking at it from the 
opposite side, the team with the better pitching has won just 14 of 39 
playoff series.   I wrote then (with the playoff outcomes updated through 
2008):

So does good pitching beat good hitting in the playoffs? Isn't that the 
axiom? Let's put that to the test, albeit on a relatively small scale.

We have 8 years in our record (more seasons than that, of course, but only 
8 with accurate data). In these 8 years, their have been 24 playoffs 
series. 12 times, 1 playoff team had a better ERA and Runs Per Game total 
during the season than the other ... the team that was better in both of 
those stats won 7 of the 12. 11 times, 1 playoff team had a better scoring 
team, but was facing a team with a better ERA ... the better scoring team 
won 7 of those 11 series. In the 2003 series, Steve and Chris met, having 
scored the same amount of regular season runs, with Steve posting a better 
ERA during the season ... and as we know, the better pitching team lost 
that series. All told, better pitching teams have won only 11 of the 24 
playoff series in our recorded history, with just a 4-8 record when they 
do not have a better hitting team as well.

Here's the breakdown:

Better Both (12-7 thru 2003)
1996 ---
1997 1-1
1998 0-2
1999 1-2
2000 1-0
2001 1-0
2002 1-0
2003 2-0
2004 ---
2005 1-1
2006 1-1
2007 2-0
2008 1-0

Better Scoring (12-7 thru 2003)
1996 2-1
1997 0-1
1998 1-0
1999 ---
2000 1-1
2001 2-0
2002 1-1
2003 ---
2004 1-2
2005 1-0
2006 0-1
2007 1-0
2008 2-0

Tied Scoring, Better Pitching
2003 0-1

http://www.geocities.com/k_h_klein/dnfiles_2003/playoff_horp.html