Jordan Zimmermann, in a starting rotation with Stephen Strasburg and Gio Gonzalez, doesn’t get much attention. But did you know he led the Nationals pitching staff in quality starts last year? And that he leads the major leagues in WHIP this year? Zimmermann’s path to success, especially so far this year, defies basic sabermetric assumptions and is worth examining more closely.

Zimmermann is built like a power pitcher. He’s a sturdy 6’2”, 220 lbs., and he has a fastball that averages better than 94 mph. He has a hard slider and much-improved curveball as his secondary pitches, as well as an occasional changeup. He has the pure “stuff” to strike out 200 batters a season.

Steve McCatty, Zimmermann’s pitching coach, does not want him to be a strikeout pitcher. McCatty believes that strikeouts are a bad goal for pitchers because they drive up pitch counts, while carefully “pitching to contact” is the correct approach. Zimmermann said recently, “You try to make nasty pitches in the dirt, and if the hitters don’t swing, you get them back in the count and you end up throwing six or seven pitches to a hitter.”

In the offseason, Ben Lindbergh looked at Zimmermann’s high fastball usage, high foul rate, and low strikeout rate, combined with mediocre pitch efficiency, and concluded very reasonably that Zimmermann ought to try using his breaking stuff more and feel free to pitch outside of the strike zone to get more K’s.

On the whole, after all, statistics show McCatty’s assumptions are wrong. But Zimmermann first month this season has mostly been a vindication of the McCatty system.

Zimmermann’s strikeout rate is well below average at 5.5/9 innings and 16 percent of batters overall. A low strikeout rate is bad for pitchers because it places pressure on them to get outs through balls in play, or so the theory goes. Zimmermann has somehow been able to hold batters to a .188 BABIP this year—including a paltry .213 on pitches inside the strike zone. His groundball rate is up to 51 percent this year, from 43 percent last year. He’s also held himself to a tiny walk rate of 1.4/9 innings, or just 4.2 percent.

The most amazing part of it is that Zimmermann actually is pitching to contact when he gets these outs. His fastball usage has increased this year, and so has the fastball’s groundball percentage. Sixty-six percent of his pitches have been strikes, and 55 percent have been in the strike zone (while the league average is just 49 percent). He’s also been able to cut down on his foul/swing rate from last season, when it was one of the league’s highest. His home run rate is also quite low, at just 5.4 percent of the fly balls he’s allowed, or two in 44 innings.

What that means is Zimmermann has found, at least for now, his holy grail. He’s needed just 4.36 pitches/out, meaning he could record a complete game on just 118 pitches given an average performance this year. Indeed, he’s already thrown two complete games this year, including a one-hit shutout of the Cincinnati Reds that is undoubtedly one of the greatest games pitched in Nationals history.

What this means is that hitters are seeing the pitches out of Zimmermann’s hand, convincing themselves they can hit the ball hard, making contact, and then consistently making outs. It’s an extremely difficult pattern to maintain.

For Zimmermann to continue his success in the same fashion, mechanical consistency and command of his pitches will be essential. If he loses the ability to spot his pitches, batters will likely become less aggressive—thus requiring more pitches to record an out. He also makes himself dependent on a defense that has had a couple of hiccups this year. If the .188 BABIP figure is a result entirely of luck, rather than skill, Zimmermann’s strategy would eventually become a great deal of “pitching to contact” with runners on base—a dangerous way to live, when a guy has the stuff to strike guys out. His BABIP will regress, but whether or not it will go back to league average and suggest a change in strategy will tell us whether Zimmermann has entirely been lucky so far, or whether he’s really figured something out.

A good test of Zim’s strategy comes tonight against the Tigers. Detroit’s hitters have good plate discipline and good contact rates, as well as good power. If Zimmermann’s aggressive strike throwing gets hit hard early, he may need to adjust and look for the strikeout with his breaking pitches. But if he can hold up against the likes of Miguel Cabrera and Prince Fielder, he will demonstrate definitively that he has found a formula that could soon make him a household name.

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I recall Matt Cain was for many years the sabermetric whipping boy, compiling improbably low BABIP rates. Are there any similarities with the Zim?
There are some similarities. Cain is very fastball-heavy, although slightly less so recently. He also had above-average strike zone tendences, but those have also diminished somewhat. One thing he definitely has done, like Zimmermann, is outpitch his FIP.
Do we know if Zimmermann is pitching to contact until he needs to try and get a K?
In theory, if he has retained his K skill but chooses not to use it, then I guess he may still be OK when his BABIP regresses *IF* he can still get Ks when he starts getting more baserunners. His ERA would still likely rise as he won't always get a K when he needs it. But he should still be OK. I do agree the Tigers will be a good test.
According to Zimmermann, he was more interested in strikeouts before his Tommy John surgery. He was able to strike guys out a 9.1 per 9 innings in 2009.

His stuff being what it is, and the fact that he says he's trying to avoid strikeouts now, I'm pretty sure he could get it above the 16.4% it is now. (That's also down from last season.)

Changing approaches definitely comes with risks, which is why he should only do it if this past month proves to be a total fluke (i.e., if his BABIP becomes league average or higher AND he's not striking guys out).
Greg Maddux out pitched his FIP by over 1 run from 1992 to 1998. Pretty large sample. Too bad we don't have pitch fx for his prime years because I think we can agree it was no fluke. It is also why I like baseball reference's WAR over Fangraphs'.
I went to the game last night when Zimmermann finally faced the Tigers. The only hitter he threw a lot of offspeed stuff to was (surprise) Cabrera, where he was trying to get first-pitch strikes with the slider and also get the curve over. Cabrera hit the ball hard multiple times, but only one of them fell for a hit. Double-N had five non-Anibal Sanchez strikeouts, two of Prince Fielder, who he was challenging with heat - Prince got a titanic double to lead off the second but was otherwise neutralized.

Overall, a strong outing anytime you hold the Tigers offense to one run over 7 innings, although there were a few hits sprinkled through there. My perception was that Zimmermann didn't change his approach so much as look for the strikeout when the patient Tigers hitters worked the count into two-strike territory. He was pounding the zone early in the count trying to induce weak contact, and more often than not got it (again, except against Cabrera. I don't know how that guy ever makes outs).