It's just spring training...It's tough to comment on spring training, particularly this early. While the Nats have won four of their first five ST games (and, as I write this, are trailing Detroit, 1-3 after 3), that isn't saying anything at all, for a number of reasons. First, people are just shaking off the rust. Particularly pitchers, who will often focus on honing one or two pitches, where nobody (who matters) will care if they get shelled. Also, by the middle of games, everyone who's playing is a prospect that generally won't even make the 25-man roster.
As a result, I'm not at all worried that Day did horribly in his first start. It's a bit more horrible that Hinkley did even worse in his second opportunity than he did in his first, giving up 6 runs and 8 hits in just two innings, spanning 56 pitches. It doesn't matter much, as he was a long shot to break onto the roster, anyway. It just comes close to sealing that return to the minors.
Rauch and Patterson have both looked good so far, but we're a long way from finding out if they can take the 5th spot. Chavez hasn't been doing horribly, and is showing a lot of dedication. For example, I saw on a message board that, after the Mets game on Saturday, he drove 65 miles to pinch hit in the Astros game.
Also, Svrluga posts in his blog that some obvious cuts have already been made, sending a bunch of prospects back to the minor league camp. They're no big deal, as none of them were even a long shot to head up to DC.
Also, the Post points out that the Nats and O's will play each other one way or another next year, because the AL East and NL East will be playing each other. Besides that, I'd be shocked if they're not "natural rivals" after this year, as has been widely speculated. Apparently, pretty much everybody in baseball would be shocked as well.