I wouldn't worry too much about the OF/1B depth. There's still plenty of time to add bodies there for depth. Not many teams have starting caliber outfielders or 1st baseman sitting on the bench, especially in the NL. Right now, we have McLouth, Frandsen, and Kobernus who can play in a pinch. Moore also. At 1b, Moore and Frandsen can back play for a few games.
We're actually in pretty good shape in the OF. We have one of our top prospects that is borderline MLB ready in Taylor. That gives you options. If an OF gets hurt and goes on the DL, he gets the call. If Zimmerman gets hurt and is out awhile, you call on Moore. If he's not cutting it, you may be able to reach tk Skole for a couple weeks. Looking even further, if the OF is healthy, you could move Werth to first and put Taylor in his spot.
Multuple injuries can happen at the same time but nobody has multiple starting caliber players on the bench. That's wh3n you make a move. And as a result of this trade, the depth in our organization has gotten a little better.