Exploiting Inefficiencies in Future Major League Rules

Quirky new rules go from independent league to the big leagues.

It’s no secret that MLB has been looking at possible rule changes to both speed up pace of play and infuse more action into their games. The shortened 2020 season saw the introduction of a slew of rule changes that teams were forced to quickly react to. Among the changes were the three batter minimum, new roster rules, a universal DH, seven-inning doubleheaders, and a runner on second base in extras. That list doesn’t include the official announcement of postseason expansion from 10 to 16 teams mere hours before the first pitch of the season.

Of course, many of these changes were the result of the COVID-19 pandemic impacting the shortened 2020 season. However, that didn’t change the amount of time each team’s front office had to understand how the new changes affected their own strategies and rosters moving forward. It’s easy to write off these sudden changes as one time happenings, but each front office has been tasked with navigating through a sizable portion of this offseason without any official word on a new DH or playoff format. These decisions are not insignificant and certainly affect a team’s future decisions in real-time.

So, as not to be blindsided by future changes, let’s take a look at some of the rules that have been implemented by MLB in the Atlantic League of Professional Baseball, an independent league that is now an MLB Partner League.


2019 Experimental Atlantic League Rules


  • The pitcher is required to step off the rubber to attempt a pickoff
  • One (1) foul bunt is permitted with two strikes before a strikeout is called
  • Batters may “steal” first base on any pitch not caught in flight (the batter can be thrown out if he attempts to run)
  • “Check swing” rule made more batter-friendly
  • 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)
  • Home plate umpire assisted by the radar tracking system and an MLB-defined strike zone
  • No mound visits permitted by players or coaches other than pitching changes and medical visits
  • Pitchers must face a minimum of three batters or reach the end of an inning before they can exit the game unless the pitcher becomes injured
  • Increase the size of bases from 15 inches square to 18 inches square
  • The time between innings and pitching changes reduced from 2:05 to 1:45

You’ll notice that one of these rules, the three batter minimum, originally debuted in the Atlantic League and already got introduced at the big league level. So, it’s likely that we see the introduction of one or more of these experimental rules in MLB in the coming years. For the 2020 season, I created an intern role with the Lancaster Barnstormers and my curiosities led me to the quirky Atlantic League rulebook. In particular, I focused on two rules that teams in the league could explore and exploit.


One Free Foul Bunt with Two Strikes


The first rule I looked at was “one foul bunt is permitted with two strikes before a strikeout is called”. This rule serves as a significant advantage to hitters and attempts to revive the lost art of the bunt. The rule allows hitters another avenue to reach base in two-strike counts when their chances of reaching base are the lowest. Aside from just reaching base on a two-strike bunt though, the rule forces the defense to at least be aware of the possibility of a bunt. If teams respect the bunt, this can open up the left side of the infield for additional base hits. If teams don’t respect the bunt, hitters will be able to attempt a bunt single at no additional consequence should their attempt go foul.

Many people might think this rule change would have a limited impact on a hitter’s decision to bunt. It may seem like fair reasoning considering the minimal amount of bunts seen when the shift is currently deployed. However, these decisions are currently made in zero and one strike counts. Hitters have a much higher chance of doing damage in those counts in comparison to less advantageous two-strike counts. It would be surprising to see defensive alignments that fail to counter bunt attempts that come at no consequence. We also have already seen hitters attempt to bunt for a base hit with two strikes in MLB. Once both hitters and fielders adjust, we’re likely to see defenses protect against this play, meaning we won’t see an abundance of two-strike bunt attempts. This essentially means the rule would open up the left side of infields with two strikes. That’s an effect of the rule, but it’s certainly not a very exciting one.

Let’s move on to the inefficiency of this rule that could lead to some interesting strategy. As an Atlantic League intern, I was prepared to recommend a strategy that at peak execution could have provided a significant advantage in the running game. Anytime a hitter reached two strikes with an average or better baserunner on first, the strategy called for a steal.

If the two-strike pitch was headed for the strike zone, the batter would foul bunt the pitch off, thus protecting both himself from a strikeout and the runner from a caught stealing. If the pitch was a fastball outside of the strike zone, the batter would still foul bunt the pitch off to protect the runner. If the pitch was off-speed and outside of the strike zone, the batter would let the pitch go and the runner would steal second base. The expected stolen base percentage on these off-speed pitches—many of which would bounce in the dirt on two-strike counts—would be astronomically high.

If a team were able to collectively handle the bat well enough to foul bunt off strikes and fastballs, they could attempt stolen bases on off-speed pitches outside of the zone at no consequence. The potential advantage of this could be substantial given the sheer amount of chances a team might have to execute this strategy. Though, it’s likely some hitters may not master the foul bunting skill, which would limit the strategy’s comprehensive effectiveness. It’s also likely that professional baseball players may not be open to this strategy. It wouldn’t be the first time Atlantic League players rebelled or coaches spoke out against the league’s gimmicks.

This type of aggressive strategy doesn’t have an obvious counter move. With two strikes, the pitcher could throw pitch outs that the batter has a difficult time fouling off. However, even these pitches could potentially be foul bunted. It’s also not ideal to be throwing pitch outs every time there are two strikes and a runner on base. In addition, the strategy could be deployed with a full count, eliminating the pitch out as a possible counter move.

Even without a runner on, the strategy could also be deployed in full counts to make the pitcher throw two consecutive strikes to avoid a walk. When a batter reaches a full count or any two-strike count, they could square around to foul bunt the next pitch in the strike zone. This would essentially allow hitters to walk or work the count into their favor at the small expense of using up their free foul bunt with two strikes. With no great way to defend against the play, it’s likely more teams in the league would begin to copy the strategy. Eventually, a bunch of teams would be foul bunting and stealing in two strikes counts.

The broad effects of this strategy include increasing pitch counts, stolen bases, and time of the game. Not to mention that fans would be forced to watch purposeful foul bunts. The intention of the rule is certainly plausible as it aims to bring back the lost art of the bunt. However, the unintended consequences of the rule make it something that won’t advance from Atlantic League guinea pig to major league spotlight without its consequences.


Automatic Ball Strike System


The second rule I looked at was “the home plate umpire will be assisted by a radar tracking system and an MLB-defined strike zone”. This rule has been talked about for years in professional baseball circles and finally made its debut at the 2019 Atlantic League All-Star Game. I was lucky enough to be in attendance at that game, which featured the home plate umpire wearing AirPods to assist with ball and strike calls. On a quick side note, that game was ultimately decided by a home run derby instead of a traditional extra innings format. For now, though, let’s leave our dreams of extra-inning home run derbies on the backburner. The system was certainly a bit shaky in its infant stage. It missed numerous calls and provided delayed calls in its debut. It also provided its fair share of controversy for the remainder of the 2019 season. Despite the system’s early struggles, it may be here to stay.



It wouldn’t be a shock to see MLB move towards an automatic ball strike system very soon. The Trackman version of the system has already made the jump to affiliated minor league baseball and the Arizona Fall League. Back in March, MLB was testing out the new Hawk-Eye technology for automatic balls and strikes in the background of spring training games. With its implementation seemingly inevitable, it would be smart for front offices to begin looking at the potential impacts of an automatic ball strike system. Here are a few pertinent questions to ask:

  • How does the system affect hitters?
  • How does the system affect pitchers?
  • Will certain players benefit from the system over others?
  • How will the system affect the value of catchers?
  • How quickly will players be able to adjust to the system?

It’s tough to know exactly how the system will affect hitters and pitchers without direct access to the Trackman data from the Atlantic League. From conversations with people in the league, I surmise that there are certain pitches that hitters are not used to being called strikes. Namely, the system tended to catch hitters off guard with high strike calls, especially on breaking balls. This can likely be explained by human bias in umpires against high breaking balls, which have traditionally been called balls.

Understanding how human bias affects umpire’s current strike zones will be the key to quickly adjusting to the differences of an automatic ball strike system. In The Inside Game: Bad Calls, Strange Moves, and What Baseball Behavior Teaches Us About Ourselves, Keith Law discusses two ways that umpires allow human bias to impact their ball and strike calls.

The first way is by basing their calls off the results of previous pitches. Humans are subject to a bias known as the anchoring effect. This effect can best be described as a cognitive bias where an individual depends too heavily on an initial piece of information offered to make subsequent judgments during decision making. In theory, the previous pitch being called a ball or strike should be independent of the next pitch being called a ball or strike.

With human bias though, this is not the case. In a 2016 study, a significant effect was found that umpires were more likely to call a pitch a ball if they called the previous pitch a strike. The effect was small but became much larger if the second pitch of the sequence was ambiguous, or on the edges of the strike zone.

The second way that umpires are affected by human biases is through impact aversion, which is a bias that causes humans to lean toward doing nothing rather than doing something. A study in Scorecasting: The Hidden Influences Behind How Sports Are Played and Games are Won found that umpires made correct ball or strike calls 85.6 percent of the time. In 0-2 counts though, umpires’ only made the correct call 61 percent of the time. Likewise, in 3-0 counts, umpires’ only made the correct call 80 percent of the time.

In both situations, we can attribute this to umpires being averse to ending the at-bat with an impact call. This human bias in umpires causes the run values of 0-2 and 3-0 counts to be artificially skewed back toward zero. This is because human umpires tend to call more balls in 0-2 counts and more strikes in 3-0 counts.

As an offense, this means it would be harder to produce runs in 0-2 counts with the system than with a human umpire. On the other hand, it would be easier to produce runs in 3-0 counts with the system than with a human umpire. The system will not provide an advantage to hitters in 0-2 counts or to pitchers in 3-0 counts. Machines have no biases and therefore treat every pitch as an independent event regardless of the previous pitch, count, or game situation.

The introduction of an automatic ball strike system will also render useless the skill of framing for catchers. No longer will teams discern who the top defensive catchers are based on framing. If they haven’t already, it’s fair to assume that teams will start placing a higher emphasis on catcher game calling. At this point, some teams probably do more assuming about a catcher’s ability to call a game based on his reputation, veteran status, and rapport with pitchers. These are all relevant factors, but not exactly quantifiable attributes. This is an area of catching that will need to be better examined.

The best way to take advantage of this is to build a model that recommends what pitch and location to throw based on pitcher and hitter tendencies, game situation, count, and previous pitch outcomes. At the end of each pitch, the type of pitch and location the catcher called would be manually recorded. After each pitch, the catcher would receive a grade based upon the expected level of success his call had.

Take for example, if the model recommends a high fastball and the catcher calls for an inside fastball. The catcher would likely receive a better grade than had he called for an outside breaking ball. Essentially, the model would put in hierarchical order the best pitches to throw for that individual situation. If the catcher calls the 9th ranked combination, he would be graded better than if he had called the 10th ranked combination. It would have to include an order of recommendations and then a grade based upon that list. This would theoretically move a team closer to identifying baseball’s best game callers when framing becomes extinct.

In the next few years, MLB is likely to introduce more rules first tested out in the Atlantic League. Teams will have to understand and exploit the inefficiencies of these rules without having prior experience with them. The front offices that have started preparing the earliest for these changes may have an advantage over their competitors. A new era for the baseball rulebook will soon be upon us. You don’t have to look any further than the Atlantic League for real evidence of how these changes will impact major league games.

Featured Image Photo by Aideal Hwa/Unsplash | Adapted by Michael Packard (@designsbypack on Twitter & IG) | Photo by Julio Cortez/AP

Ben Reed

Ben is a senior economics major at Oberlin College where he is also a shortstop. He's working this summer in baseball strategy with the Lancaster Barnstormers.

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