Clemens is an obvious lock for the all-star game. If you simply look at production, Ensberg should be easily make it too. Among NL 3rd basemen, he's #1 in OPS, #1 in Slugging, tied #1 in Home Runs, #2 in RBIs. The only Problem with Ensberg is his low BA. Oswalt, in my opinion, has no chance. There are simply too many pitchers who either had better seasons, or really win-loss stats despite having crappier ERAs.
Who came up with this stupid rule that every team has to have an all star participant? Does anybody besides five people in Kansas City really care is some scrub on the Royals gets a half inning in the outfield in the 9th?