MLB Is Testing Ideas in the Atlantic League

Last week, Major League Baseball and the independent Atlantic League announced a partnership to test certain rule changes that could be coming to MLB. This deal is noteworthy for a few reasons. First, the introduction of an automatic strike zone suggests that the role of big league umpires could be changing. Second, the rule changes themselves, which range from the interesting to the just plain weird, suggest a continued emphasis on more balls being put in play, and greater action on the field. Third, the Atlantic League will become the first unaffiliated league with access to Trackman data, creating a more robust way of seeing potential differences between the leagues’ talent levels, and potentially creating a new pipeline for prospective major leaguers.

Let’s start with the rule changes themselves.

The following new rules will be in place for the 2019 Atlantic League Championship Season:

• Home-plate umpire assisted in calling balls and strikes by a TrackMan radar tracking system
• No mound visits permitted by players or coaches other than for pitching changes or medical issues
• Pitchers must face a minimum of three batters, or reach the end of an inning before they exit the game, unless the pitcher becomes injured
• Increase size of first, second and third base from 15 inches square to 18 inches square
• Require two infielders to be on each side of second base when a pitch is released (if not, the ball is dead and the umpire shall call a ball)
• Time between innings and pitching changes reduced from 2:05 to 1:45
• Distance from pitching rubber to home plate extended 24 inches, in the second half of the season only; with no change to mound height or slope.

Robot umpires? Robot umpires! We’ve talked before about how, given the way the ball and strike rules are currently worded, introducing robot umps would require pretty significant rule changes. Now some umpires have been maligned (often fairly) for the eccentricities of their unique strike zones. Joe West and Angel Hernandez certainly come to mind. But while having an automated ball and strike system might help, the difference might be less than you think.

How accurate robot umps will be relative to their human counterparts remains an open question. Missing 10% of all calls is, well, less than ideal, and the limited spread between Wegner and Little on the one hand, and Staring Joe West on the other, suggests that umpire quality, at least in this one area, is pretty uniform; other research, like this piece from Michael Lopez and Sadie Lewis, suggests that there is an appreciable range of quality among major league umpires.

On the other hand, what limited data we have suggests that an automated strike zone, at its current level of development, might be even worse than the one we see now. As Rob Arthur wrote a couple of years ago for FiveThirtyEight,

Errors in both horizontal and vertical movement have never been higher in the four years that Statcast has made some of its data publicly available.² So it’s not just your imagination as you watch the game on TV: In-broadcast representations of the strike zone (like FoxTrax) take their data from Statcast, and Statcast’s errors, in turn, have bred anger with umpires and confusion over how pitches are being called.

Statcast runs into the most trouble when it’s quantifying pitch break, or the degree to which pitches move up and down or side to side as they travel between the mound and the plate. Third-party observers have catalogued numerous inaccuracies with Statcast’s break numbers. “It appears that the current Statcast/TrackMan h[orizontal]/v[ertical] break can be up to 3 inches divergent from the truth, simply comparing it to 2016 PITCHf/x data,” said Kyle Boddy, a data-driven trainer with multiple MLB clients.

Three-inch disparities, for the record, are par for the course for Angel Hernandez. Would we really be okay with robot umps that have Hernandez’s accuracy? Probably not, but perhaps this can help move the technology forward.

There’s one more interesting effect of this new partnership for umpires. Major league umpires are potentially watching their employer test their replacements in real time. In fact, if I had to guess, I’d say this is a big reason why MLB chose the Atlantic League, as opposed to an affiliated minor league, to try this out – so as to avoid the umpires’ union publicly protesting the plan. It will be interesting to see what measures their union takes, if any, in response to this development – and if the experiment is a success, how quickly the union will move to preserve its members’ jobs.

A number of the other changes will also have an effect on the balance between pitching and hitting. Moving the mound back can reduce a pitcher’s effective velocity, because it gives a hitter that much more time to recognize and adjust to a pitch. It seems pretty clear that the goal of this change, and of banning the shift, is to increase offense, but it remains to be seen what the other side effects would be. Will the extra two feet increase injury risk? Will fewer infield shifts lead to more outfield shifts? Will the additional balls put in play make a noticeable difference in how fans experience these games?

And what’s most interesting is the idea that all of these drastic rule changes are going to be tried at the same time. What we don’t know is how the people analyzing the data will be able to separate the signal from the noise and determine which of the changes is having a specific result. Is offense up because of the mound distance change, or the shift ban, or more tired pitchers?

On the flip side, the existence of Trackman and Statcast will suddenly make the Atlantic League, on the surface, a pretty desirable landing spot for players in unaffiliated ball looking for a shot at the big leagues, whether for the first time or as they make their way back from injury or poor performance. After all, they now know that major league organizations will be keeping a pretty close eye on the league this season. Rich Hill might be the most famous Atlantic League alumnus, but he’s hardly the only one.

The presence of Trackman units means that Atlantic League players, and the major league teams scouting them, will have access to a season’s worth of spin rates and exit velocities, which should help to identify talent that could pass muster in affiliated ball. On the other hand, it remains to be seen whether scouts and front offices will discount players’ performance in the unaffiliated circuit as a result of the changes being made. Will they discount hitting performances because they’re inflated by the more distant mound and the absence of shifts? Will they view pitcher performance as just too noisy given all of the variables? New paths to the majors are a good thing, and more eyeballs on the Atlantic League could help accomplish that. But it remains to be seen how those new eyes will consider what they’re seeing, and how big of a role Trackman data will play.

There’s also the possibility that this kind of scattershot testing actually reduces innovation. We’ve seen independent leagues used as testing grounds for new strategies before, made possible by the separation between MLB and unaffiliated ball. It’s possible that this new partnership will lead to greater control of the independent leagues by MLB, thereby making them less, well, independent. But at the same time, we don’t really know how this partnership will really play out. It’s just one more thing to watch as the 2019 season commences.