Edwin Jackson pitches today. If you are unclear why, some over-arching stats help explain it.
v RHP : .265 / .329 / .397
v LHP : .287 / .358 / .478
v RHB : .236 / .293 / .385
v RHB : .263 / .320 / .414
The Cards have a right-heavy line-up that does worse against RH pitching. Edwin is a right-handed pitcher who does better than Ross, a left-handed pitcher, against righty heavy line-ups.
For those of you like "Well Zimmermann was right-handed and look what they did to him!" I'd bring up two points
1) ZNN actually pitched better against lefties.
v RHB : .268 / .295 / .428
v LHB : .234 / .300 / .350
2) Yeah, well, that'll happen and there's nothing you can do about that.
Statistical analysis is a long term thing. Start Edwin vs the Cardinals 20 times and Ross vs the Cardinals 20 times and odds are very good Edwin will have the better stats at the end of this experiment. But start Edwin once and Ross once, and while you'd still expect Edwin to have the better stats, the odds drop a lot. Anything can happen in one game. All you can do is set up your best chance for success, in this case starting Edwin this afternoon, and hope it works out.
That makes me double reluctant to say anything about Chris Carpenter. The guy has started three games this year. Three! Forget small sample size, that's almost no sample size. I will say if he's healthy and on his game the Nats will have a hard time winning this game. He's better than Edwin. That being said, he's 37, coming back from injury and again, three starts, so who knows.
Any Cards hit Jackson especially well? Molina maybe (.667 with 2 homers) but that's 14 PA worth - so 3 games. I only mention it because it's SO overwhelmingly good. But again - 3 games. No real trends worth noting for the Nats vs Carpenter given the amount of at bats.
Any good news for the Nats? Well, the park favors lefties over righties a bit, especially depressing doubles by righties. The deeper gap in left is the culprit. You'd expect that then lefties might hit more homers, but the wall height discrepancy between the power alleys helps even that out.
Not much else left to say other than I really hope the sun doesn't play a major role in this game. The early start I think will help if the game can move quickly enough. If it does play a role with the Cards messing up then great! If it plays a role with the Nats messing up... there's really no excuse for that. You play there all the time, you should be better at dealing with it than opposing teams, and from what I've seen this year the Nats aren't.