I specifically heard a national talking head discussing this today. I trust who the Reds would roll out there, and to a certain extent, I don't think it would be as big a mismatch as many people feel.
The Philles have Roy Halladay, Cole Hamels, and Roy Oswalt, the Cardinals roll out Chris Carpenter and Adam Wainwright, and should the Giants make it, good luck hitting Tim Lincecum and Matt Cain.
A likely Game 1 starter in the playoffs would be Bronson Arroyo. I can't quantify it with stats and flashy numbers, but there is a trust factor I have with this guy. You know what you are getting, and I think on any given day he can match what the other team's ace is producing.
I'm not trying to say he's on the level of a Halladay or Carpenter. I'm just saying that he is capable of stepping it up. He's durable, unflappable, and has a bevy of postseason experience with the Red Sox.
Outside of Arroyo, Johnny Cueto, Mike Leake, Travis Wood, or whomever else is out there, has potential to throw an excellent game.
Another Cardinals mention: besides Chris Carpenter, they relied on guys like Jeff Suppan, Jeff Weaver, and Anthony Reyes during their 2006 World Series run.
Not exactly famous names in baseball lore, but they showed up and got the job done.
In conclusion, it's baseball, and games aren't played on paper, they are played on the field.