Aim Small, Miss Small: How Breaking Down Strike Zone Differently Reveals Brewers' Pitching Brilliance

With the first three pitches, Devin Williams dotted the outer edge of the plate with fastballs. One was too high, but the other two were called strikes--much to the consternation of the Reds dugout. They were great pitches, though, and with McLain in a 1-2 hole, Williams was then able to throw his screwball over the inner edge and catch the rookie looking outside, completing the strikeout with a whiff.

At Baseball Savant, where MLB keeps its neatest but nerdiest numbers, there are multiple ways to slice and dice the strike zone. One of them is a subdivision that essentially consists of concentric rectangles. There are four categories: Waste, Chase, Shadow, and Heart. Waste pitches, in the outermost rectangle, are either total misfires or attempts by the pitcher just to set up future offerings. Only Javier Baez-type hitters ever really engage with them. Chase pitches are a bit closer, but still clearly outside the strike zone, and the hitter just needs to identify them and lay off.

The two innermost rectangles in the chart are Shadow and Heart. The Shadow category rings the edges of the strike zone on all sides. It's where pitchers most want to live, because doing so will force hitters to swing more often but rarely result in hard contact. The danger, or one of the dangers, is in a pitch meandering into the Heart zone, which is just what it sounds like: the meaty part of the strike zone, where the league's average exit velocity is 93 miles per hour and their average launch angle is 15 degrees. By contrast, batted balls in the Shadow zone average 86.4 miles per hour. There's a difference of over .100 in expected weighted on-base average (xwOBA) between the two regions.

It's vital, then, to be able to work in the Shadow region without also spending too much time in the Heart. In one sense, this is the difference between control and command, expressed quantitatively. Teams who fill up the Chase and Waste areas will walk too many hitters, or end up behind in counts and have to use too much of the plate eventually. Those who lean too far toward Heart when they're around the zone will get hammered. You have to be able to work within the zone, but also expand it--to avoid damage, but still get strikes.

The Brewers are, perhaps, the masters of this craft for 2023. On the year, only the Cubs and Mets have thrown fewer pitches in the Heart than has the Crew. Yet, only the Dodgers, Tigers, and Twins have thrown more of their pitches in the Shadow zone. Pain in broad strokes (by combining Shadow and Heart into a category, and consolidating Chase and Waste into another), and the Brewers look average. They spend the 18th-most time around the zone and 15th-most time well beyond it. When you break it down, though, they're clearly more adept than almost anyone at working the edges. No team has allowed a lower percentage of opponents' balls in play on pitches in the Heart this year than the Brewers. 

That's why they've been so devastatingly effective against the Reds. Cincinnati is the offense that has had the highest percentage of their batted balls on Heart pitches this year. It would be unfairly reductionist to say that the Reds are just mistake hitters, but they rely on pitchers eventually caving to their pressure and throwing them something very hittable. Because the Brewers avoid that as assiduously as anyone in baseball, and also avoid veering too far the other way and putting the Reds' speedy runners on base for free, they've frustrated that approach. 

This is a credit to everyone involved in the process, from the pitchers themselves, to pitching coach Chris Hook and the overall pitching infrastructure the team has assembled, to the catchers who set the targets and help the pitchers find the (literal and figurative) edges this way. It's not as easy as overpowering hitters with 102 down the gut, but it's much more repeatable than that is, and it's easier to find pitchers who can do it. At a certain point, it becomes a culture within the pitching staff, and then everything spirals in a good direction.

Let's mix and match the numbers one more time, to clarify what we're saying here. Combine Shadow and Chase into a single category containing (on average) the most valuable pitches--the ones hitters might swing at, but on which they can't hurt you--and the Brewers trail only the Rangers and the Tigers in the share of their pitches that end up there. Because the Brewers' hurlers have the Tigers' beat on sheer stuff, it's fair to say that the only pitching staff executing better than Milwaukee's this season is that of the AL West-leading Rangers. It's hardly news that, if Craig Counsell and company win the NL Central, it will be mostly thanks to the pitching staff. Still, this is an illuminating look at the ways in which they've effected that dominance.