Another Way Robot Umps Would Help by Travis Sawchik July 13, 2017 Jon Roegele is the leading authority on strike-zone changes, and I recommend you read his midseason update of the strike zone that was published at The Hardball Times yesterday. There are a number of interesting findings and developments in the piece, but the headline is that the strike zone is contracting for a second consecutive season after it shrunk for the first time in the PITCHf/x era last season. In 2015, the strike zone measured 475 square inches, according to Roegele, and 50 square inches in the area 21 inches above the ground and down (i.e. the bottom of the zone and below). It declined to 474 and 45 inches, respectively, last season, and to 464 and 43 square inches to date this season. A smaller strike zone likely has played some role in the run-scoring surge of the last 48 months, and a smaller strike zone figures to have all sorts of consequences. Interestingly, despite the strike zone having shrunk last season and having continued to contract this season, the number of pitches in the lower portion of the strike zone and below have increased this season (30.5%) from 30.0% in 2016 and 29.8% in 2015. And it’s not just more breaking balls and changeups being thrown for chases below the zone; the percentage of fastballs thrown down is slightly up this season (19.4%) compared to 2015 (19.1%), according to data provided by Baseball Savant’s detailed zones. Pitchers are throwing down more often even as the strike zone shrinks, even as batters have become more skilled at driving the low pitch. This suggests that it’s not so easy to change, that pitchers have been conditioned and programmed to target that area. (Or that not enough pitchers are browsing pitch-location data during their idle time.) It makes sense to think of the power spike in baseball as a uniform change, but that spike has actually occurred in certain parts of the strike zone more prominently than others. Consider, for example, this chart of the league’s isolated slugging by zone in 2008: And then the same thing for 2017: A decade later, the ISO mark in the top left of the zone has actually decreased by a single point, from .183 to .182. The areas middle and low, however, have increased by 30 points in most cases. That speaks to a fundamental change not just in overall power, but specific approach, from batters. One significant implication of an evolving strike zone — of an inconsistent zone — that perhaps hasn’t received as much attention is the preparation aspect from both the perspective of the individual player and the club. How do you go about planning and preparing as a player when you don’t know how the strike zone will play in a given year? How do you go about building a team as a member of a front office if you don’t know how large the strike zone will be and where the biases will be located? For instance, entering the 2016 season, if you were a decision-maker for a club, you might want to consider — perhaps you ought to have attempted — to take advantage of a strike zone that had grown every year in the PITCHf/x era, and grown in a particular place: in the lower regions of the strike zone and below it. Perhaps you invest heavily in two-seam, sinking-fastball pitchers and target an elite pitch-framing catcher, as it’s that lower part of the strike zone where most of the value of framing resides. Perhaps you place more focus and emphasis on having your pitchers target the lower part of the strike zone from the top to bottom of your system. And what if, after doing all that, the lower part of the zone suddenly begins to dry up? Earlier this season, I asked Milwaukee reliever Jared Hughes, who has relied on peppering his sinker down in the zone throughout his career, about how he is adapting in an era when the strike zone is contracting, at a time when batters have become more proficient at driving the lower pitch. Said Hughes: “If your swing is geared to the lower pitch there might be something else there you can’t get to. In my opinion, every swing, every approach, there is a way to get a hitter out,” Hughes said. “The thing is if I can find a way to have a strength up. To find something to go to up there if I think i need, which I think I do.” Hughes is trying to evolve, though he’s doing so more through pitch type than location. He’s evolving on the fly successfully. Among relievers who have thrown at least 100 sliders, he has the game’s top swing-and-miss rate, and for his career he gets about as many whiffs per swing as Chris Sale via the pitch. Hughes’ sinker was so good, he was perhaps under-utilizing his slider. After being released by the Pirates this spring, Hughes has a 2.92 ERA and 3.68 FIP for the Brewers. Of course, not every player can adjust so quickly. And if a team has invested too heavily in a strategy to take advantage of soon-to-be-defunct trend, making a change at an organization-wide level can be akin to turning around an aircraft carrier. Another interesting finding from Roegele is that the gulf between the size of the zone between left-handed and right-handed hitters continues to grow. Wrote Roegele: The lack of sustained strike calling on the inside part of the plate to left-handed hitters appears to be the most obvious area remaining where the league could stand to improve in steering its strike zone toward the rulebook definition. In 2012, right-handed hitters posted a superior isolated-slugging mark (.152) compared to lefties (.149), and the strikeout rates were nearly even (19.7% for righties an 19.9% for lefties). To date in 2017, lefties have an advantage both in isolated power (.174 to .168) and in strikeout rate (20.6% to 22.2%). If you’re employed in a front office, it would seem to make some sense to place an even greater value on left-handed hitters, if this trend continues, if lefties continue to enjoy a more favorable strike zone. Fans clamor for robot umps when calls go against their clubs. But perhaps more teams and more players will be calling for robot umps for the sake of consistency, for the purposes of planning. While robot umps might not call a perfect zone, particularly at its northern and southern boundaries, robot umps could — eventually — provide a more consistent one.