Yeah, a sweep is obviously the best-case scenario. Even if the Nats take the first two, it's very possible that Carpenter beats Jackson in Game 3...but then they have to win two more, on the road. That's an uphill climb for the Cardinals.
Anything can happen, but I'll be pretty surprised if this series goes to a Game 5.
I think Wainwright and Carpenter are going games 1 and 2. You act like those are sure wins for Nats.