It's been assumed since the end of the season that Chien-Ming Wang would be back in a Nationals uniform in 2012. Now that it's official that he will be, the Nationals' rotation has some shape for next season, and it's clear the battle to get a spot in it will be heated.
Here's what we know: Stephen Strasburg and Jordan Zimmermann are virtual locks to be the top two starters. Wang will almost assuredly be there, and John Lannan should be there, as well. The Nationals essentially could have four of five spots accounted for headed into the spring, with young arms like Ross Detwiler, Tommy Milone, Brad Peacock fighting for the final spot.
Now, with so many pitchers penciled in and so many others fighting to get in to the rotation, it might seem like the Nationals have enough options to put their rotation together without adding anyone this winter. I'd caution against assuming they're good to go, however. Strasburg is going to throw, at most, 160 innings, and it would seem like Zimmermann will probably wind up around 190 or so. Lannan is good for 185-200 innings, but Wang is still only 11 major league starts removed from his lengthy rehab after shoulder surgery. The Nationals have plenty of promising options, but three of their four starters will have spent time on the 60-day disabled list after major surgery within the last two years. All indications are that Strasburg, Zimmermann and Wang are healthy, but there's still not a horse in that group that can be counted on for 200-plus innings.
The name that makes sense to me, as I've been saying for a while, is White Sox left-hander Mark Buehrle, who has logged more than 200 innings in 11 consecutive seasons. The four-time All-Star is a free agent this year, and though there have been indicators he wants to return to the White Sox (or possibly go to the Cardinals, his hometown team), the Nationals may be able to sway him in their direction with the right offer. Industry sources believe the team will be interested in Buehrle this winter, and though there are plenty of deep-pocketed teams (the Yankees, Cardinals and Cubs among them) in the market for pitching, it wouldn't be surprising to see the Nationals dive in.
It would also make sense; as good as the Nationals' rotation looks like it could be next year, they still need a dependable starter to round it out.