Nationals' Starters Pitching Down, to Expectations?

Jon Roegele penned an insightful article over at The Hardball Times earlier this month about baseball's expanding strike zone. Specifically, Roegele found that the zone was about 436 square inches as far back as 2008, increased to 459 square inches in 2013, and then achieved a seven-year peak in 2014 of a whopping 475 square inches.

Roegele also found that the zone "is stretching like crazy down from the knees as if it is under the clutches of gravity."

To him, "it is clear from this table that the falling bottom of the strike zone is accounting for the entire growth of the zone as a whole."

Below are his excellent zone comparison images to give you a better idea of where strikes are being called now against 2009; the box is just for frame of reference:

via The Hardball Times

So, yea -- offense as a whole has been down, but maybe that's not that shocking given the rise of specialized bullpens, a dearth of offensive talent, and 47 extra square inches of space below 1.75 feet, or 21 inches, as against 2009. Roegele also found that more pitchers have been attacking the lower part of the zone, and hitters, in turn, are also offering more than 2013.

Nats' Starters: 2013 versus 2014

What does this have to do with the Nationals? I was curious if the team was keen to this development -- Roegele notes several studies in recent years showing this -- and if that was reflected in the starters' approach. To examine, I used the indispensable Baseball Savant to run some Pitch F/X searches for certain results between 1.5 feet and 1.75 feet above the ground, since the 2014 images above suggest that's where the change is taking place. I used horizontal measurements of one foot to either side of the plate to get a nice, low zone target.

There were four common starters between 2013 and 2014 -- Stephen Strasburg, Gio Gonzalez, Jordan Zimmermann, and Tanner Roark.

Here's how their percentage of pitches between 1.5 and 1.75 feet (the expanded part of the strike zone) breaks down:

Even though D.C.'s four starters pitched down more often this past season, that difference is pretty much due to Strasburg alone. Newcomer Doug Fister is no great help either, as just 5.16% of his pitches ended up in the bottom quarter-foot of the strike zone.

Granted, a two-foot wide, three-inch high target is darn near impossible to aim at and hit with regularity, never mind as pitchers sequence through different locations in the strike zone to keep hitters off balance. And there are obvious pitcher-arsenal considerations and count situations to consider when thinking about whether to pitch down. Anyway, it's no shocker that we don't see a significant -- say, 5% or more -- difference between seasons.

But that doesn't mean each percentage point is insignificant, particularly considering the more salient question might be whether the Nats earned more strikes in this zone than last year. By a couple different measurements, that answer is yes.

Although Strasburg, Zimmermann, Gonzalez, and Roark averaged about the same amount of pitches between 1.5 and 1.75 feet in 2013 and 2014, they got seventy-five extra strikes in 2014. Of course, that foursome pitched a lot more in 2014 than 2013 -- mostly due to Roark's emergence -- so the raw totals probably aren't a big surprise (Roark saw 29 extra strikes in this zone over his 168 extra innings tossed in '14, or 38% of the increase, for instance).

The ratio of called strikes to balls is a better look at low zone results, given the difference in innings pitched. Using that metric, it's clear the D.C. quartet saw more success down low in 2014:

I guess the results could support the conclusion that D.C.'s starters were intentionally pitching to an area of advantage, although there are plenty of other explanations and random variation to account for. At the same time, Rizzo and company have shown they can recognize and exploit trends, so maybe we shouldn't dismiss the idea that the team is trying to capitalize on this particular development just yet.

The N.L. East

Groundbreaking news here: context for statistics is important. To get a better idea of low zone performance by Washington, I looked at the other N.L. East clubs to figure out how often their pitchers threw low. Specifically, I took the top five starters per team by innings pitched, and ran the same search on Baseball Savant for pitches between 1.5 and 1.75 feet off the ground, and a foot to either side of the plate.

First, here are the averages by team:

Almost every team was within a percentage point when throwing low; it equaled out to about ~750-850 pitches total per top 5 starters (the Nats had 830 pitches in the target area). Obviously, there's no direct correlation to team success; Philadelphia pitched in the new area of the strike zone the most, and they finished last in the division.

But when we narrow the results and look at the called strike-to-ball ratio, Philadelphia didn't profit as much from their approach as two other teams, including the Nats:

Washington was a, uh, close second to New York in the ratio department....not really. Anyway, D.C. did put the second best division-wide figure together, so they managed to make the most of the (relatively) low number of targets down. Looking outside the beltway, the Mets' starters were actually pretty good by FIP this past year. So, perhaps getting nearly two strikes for every ball in the low zone helped them in that respect.

Looking Ahead

What does 2014 mean for the approach of the 2015 staff? Probably not much. Pitching coach Steve McCatty will likely still advocate a pitch to contact approach, and there are plenty of good places to get weak contact other than down in the zone. Major League Baseball and umpires could also get wise to the data and decide that 2014 was either the furthest they want to go, or focus on retracting the zone somewhat.

And it's no sure thing that pitching down will result in -- very generally speaking -- good results. For example, the team's top five might not be suited to pitching low based on their approach and repertoire. Some results don't necessary bear that out though, as Zimmermann, Strasburg, Gonzalez, and Fister had success low when using RAA/100 as a benchmark. In the end, it's tough to say if throwing low more would result in better performance.

Maybe the Nats have found a good balance given the skills of their starters and the results they achieved. After all, their hurlers were at or near the league lead in many categories, and pitched the team to the best record in the National League. But in the evolving world of the MLB, no potential advantage should go unexplored. Count on D.C. to do that this offseason.