Jordan Zimmermann is having, by most measures a very good season. He leads the Nats starters in Ks (51) and ERA (3.39) while giving up the fewest BBs (15) and HRs (3). And over the last 7 starts he’s been spectacular – a 2.62 ERA, with 37 K and 10 BB in 44 2/3 IP.  He is the best pitcher on the staff right now, and at only 25, show promise to be great for years to come.

According to Baseball Prospectus, Jordan ranks 10th in the majors in VORP among pitchers, 7th in the NL. Fangraphs puts him 9th in WAR for pitchers. His FIP (Fielding Independent Pitching) ranks 9th as well, although his xFIP, which is normalized, is much higher. This maybe due to his relatively low K/9.

But one reason why he’s doing so good without a ton of strikeouts (of the 16 starters with lower ERAs than him, only 3 have fewer Ks) is how few guys he’s walked. He has been so economical with the strike zone, that he ranks 5th in the NL in BB/9. This isn’t to suggest he doesn’t strike anyone out. He ranks 41st in the NL in Ks, but that puts squarely in first place on the Nationals. (We’re not counting hitters, right? Because Desmond and Espinosa have… oh, never mind)

That combination of a low walk rate with adequate Ks gives him something that is probably a better predictor of success than just a high K/9. It’s the K/BB rate, which is currently 3.40 for Zimmermann, putting him 13th in the NL. But if you look at what he’s done since May 1, that number jumps to 3.70, which would rank him 8th in the league. And in his last 5 starts, beginning May 12, that number jumps to 4.50 (on the back of an 11 K performance May 12) which would rank him 4th in league, only behind (get ready to be depressed) Halladay, Lee and Hamels.

Zimmermann has been great this season, especially since May 1, and he is starting to preview something that could really tip the odds of future team success in the Nationals favor – a pitcher that by many measurements is ranking in the top 20 in most important categories. Those pitchers are called “number ones” or “Aces.” This may be hard to fathom for Nats fans, who have someone else in mind when they think of an Ace. But if Zimmermann is even in that conversation, it will mean alot when Strasburg returns and JZimm is their number two pitcher.

By Charlie