Aaron Gleeman handicaps this year's rookie class. There are a ton of very strong rookies in the American League (Joe Blanton, Gustavo Chacin, Huston Street, Jonny Gomes, Scott Kazmir and Tadahito Iguchi are among them, and Joe Mauer and Chris Shelton just miss being eligible), but not so many in the National League.
The winner of the NL Rookie of the Year award will likely be a player who hasn't been with his team the whole season - as Gleeman points out, the only full-season rookies in the NL have been Garrett Atkins, Jeff Francis and Willy Taveras, and none of them have been very impressive.
Zach Duke actually leads NL rookies in VORP despite his recent injury, but fellow half-season players Ryan Howard and Jeff Francoeur (along with the Nationals' Gary Majewski) are right behind him. Gleeman ultimately gives Francoeur a lot of extra credit for his defense, which seems fair to me - his arm is just amazing. Francoeur will probably win in part because he's deserving and in part because he seems to be a media obsession, but I think Duke could still win if he opens eyes over the next few weeks and Francoeur falters.