There have been 107 WS winners, 96 had 90+ pythagorean win regular seasons. Granted, 5 of those sub 90 win teams have been in this century with the enlarging of the playoff pool, with both Cardinals winners members of that group. Let's look at the four contenders:
AL:
NYY-95
Det-87
NL:
SFG-88
StL-93
In a short series, anyone can win - the Giants have home field advantage and the Tigers have the best pitcher in baseball - but were you predicting (and I am) the picks are Yankees and Cardinals. The really unlikely outcome is having a Tigers/Giants series, as a WS where both teams had sub 90 pythags has only happened twice in 107 years (but both were in the WC era). The Giants/Cards are, of course, the past two WS winners; the previous two WS winners haven't met in the postseason since '58 (the year the Giants moved west, incidentally). The most important takeaway from the NL pythag numbers is that the Giants/Cards matchup is actually the opposite of the appearance of the regular season records. SFG won their division and had a better record; StL was the better team.
I write about the Giants occasionally; I'm picking the Cardinals in 7.
Here are the WAR (B-Ref+Davenport/2) numbers.
SFG
C Posey 8 (the best player in the series)
1B Belt 2.6
2B Scutaro 3.3
SS Crawford 3.1
3B Sandoval 3.4
LF Blanco 1.2
CF Pagan 4.5
RF Pence .6
Sanchez .3
Arias 1.7
Nady -1 (the worst position player in the series)
Theriot -.2
Huff .1
Not on the Roster: Cabrera 5(even though he missed the last quarter of the season, still our second best player this year; we should absolutely be using him in this series; the Nats shut down Strasburg and are getting killed for it; if we lose this series, mainstream analysis won't raise that we intentionally left our second best player at home; I'm raising it now)
Bumgarner 2.8
Vogelsong 2.4
Cain 5
Lincecum -2 (the worst player left in the playoffs)
Romo 2.5
Lopez .3
Affeldt .9
Kontos .5
Zito .2
Mijares .4
Mota -.3
StL
C Molina 7.3
1B Craig 2.5
2B Descalso .3
SS Kozma 1
3B Freese 4.2
LF Holliday 3.8
CF Jay 3.6
RF Beltran 3.2
Schumaker 1
Robinson .4
Chambers .2
Cruz -.1
Lynn 2.5
Carpenter .2
Lohse 4.4
Wainwright 1.7
Motte 2.6
Boggs 1.9
Rzepczynski .1
Mujica .9
Garcia 1.6
Kelly 1
Rosenthal .5
Salas .2