May 11, 2018
Nick Elam, Ph.D.

On the Scale of Self-Assuredness (where 0 = Just Spitballin’ and 10 = I’ve Got It!), writer rates this idea as a 8.

Major League Baseball continues to thrive by a number of measures, but a few troubling trends are worth addressing to ensure the game’s long-term health. Specifically, MLB justifiably seeks to shorten the overall length of games and/or improve the pace of games, and to increase the percentage of balls put into play (or conversely, to reverse the rapidly rising percentage of at-bats that end with a strikeout, walk, or home run).

Many believe that an adjustment to the strike zone could directly lead to more balls being put in play, which would indirectly lead to quicker and more exciting games. However, there is significant disagreement about what adjustment would be most effective. Some say that shrinking the strike zone is the way to go (to give batters an advantage), while others say that enlarging the strike zone is the way to go (to give pitchers an advantage), while still others say the strike zone should be left alone.

It’s easy to see the possible upside to each argument. Then again, it’s easy to see a possible major unintended consequence. A smaller strike zone might compel pitchers to throw more pitches that are easy for batters to drive. Then again, a smaller strike zone might make batters pickier, compelling them to take more pitches (leading to longer at-bats and more walks). A larger strike zone might force batters to get the bat off their shoulder. Then again, a larger strike zone might lead to even more called strikes and swings and misses (and consequently, strikeouts) than we already see. Leaving the strike zone alone is the least controversial approach, but would do nothing to address the sport’s primary concerns.

Smaller, as-is, or larger – so who’s right? Maybe all three. Maybe there’s a way to offer batters an advantage early in each at-bat, and to offer pitchers an advantage late in each at-bat, to encourage batters to put the ball in play early in an at-bat.

MLB could INTRODUCE THE DYNAMIC STRIKE ZONE CONCEPT, where the strike zone starts small for every at-bat, then expands slightly after Strike 1, then expands slightly again after Strike 2. With this concept, batters are likely to see the most favorable pitches early in an at-bat, and would change their approach accordingly.

Some impressions and considerations:

  • What would the strike zones be?

Maybe (I’m not married to these at all)…

  • With 0 strikes:
    • Top: Belt
    • Bottom: Top of knees
    • Inside: More than half of ball must be over plate
    • Outside: More than half of ball must be over plate
  • With 1 strike:
    • Top: Midpoint between shoulders and belt (current location)
    • Bottom: Center of kneecap
    • Inside: More than half of ball must be over plate
    • Outside: Any part of ball must be over plate
  • With 2 strikes:
    • Top: Armpits
    • Bottom: Hollow of knee
    • Inside: Any part of ball must be over plate
    • Outside: Any part of ball must be over plate
  • Wouldn’t this necessitate an automated strike zone?

Yes (which I favor anyway). There’s an added beauty because this could serve as the ultimate selling point for the Commissioner that MLB must adopt an automated strike zone (it’s unreasonable to implement the dynamic strike zone concept without it). The home plate umpire would still be needed for his many other responsibilities (including signaling – not judging – balls and strikes), and could now focus more intently on enforcing pace-of-play rules.

  • How would the automated dynamic strike zone adjust from pitch to pitch?

The automated static strike zone (the form commonly discussed and proposed) would have to adjust settings from batter to batter (Jose Altuve Mode, Aaron Judge Mode, etc.) anyway, so I reckon the automated dynamic strike zone would adjust settings in a similar way from pitch to pitch (Jose Altuve – 0 Strike Mode, Jose Altuve – 1 Strike Mode, etc.)

  • What would pitchers think of the change?

Overall, pitchers should probably see it as a wash. If a pitcher can walk across the hot coals of the tiny zone associated with the first strike, then things return to normal to get the second strike, and he can then go for the kill with the generous zone associated with the third strike.

Also, for better or worse, if more at-bats end quickly, starting pitchers are likely to remain in the game longer.

  • What would batters think of the change?

This is where it gets really fun, because this might have a really cool effect on batters’ approach at the plate

  • In the last few years, many batters swing for the fences, and they get three essentially-the-same chances to connect. With the dynamic strike zone concept, batters know the best pitch to hit is likely to come early. Do they still swing from the heels? If they don’t connect on that first swing, then their challenge gets tougher and tougher as the at-bat progresses. The dynamic strike zone concept just might be the force that compels batters to cut down on their swing and put the ball in play
  • Over the last generation, greater value has (rightly) been placed on drawing walks. Many batters even step into the box seeking to work a deep count and take a walk if it comes. With the dynamic strike zone, I’m not sure any batter will step into the box looking to draw a walk, or even to work the count. This concept just might be the force that compels batters to swing the bat at all
  • It’s very possible batters could be the concept’s biggest beneficiaries (by giving them a very hittable pitch early in most at-bats) and harshest critics (through a distaste – understandable to an extent – for having to adjust to different strike zones, requiring them to adjust their vision and aggressiveness from pitch to pitch; I would argue that they do this already, in part due to the human element of umpiring, and in part due to strategy and natural tendency – “expanding” the zone after each strike)


  • What would fans think of the change?

To bring it back around to the original aims of addressing pace/length of game, and reducing three-true-outcome at-bats, I think the dynamic strike zone concept could be the best of many worlds. I think it would:

  • Very likely increase balls in play (hopefully with more non-home-runs)
  • Very likely reduce walks
  • Very likely shorten length of game
  • Not necessarily have any effect on pace of game (this factor would still be dependent on pitchers, batters, and umpires honoring pace-of-game rules)
  • Probably(?) reduce home runs. I’m not sure if batters would cut down on their swing early in the at-bat (knowing that pitches get tougher as the at-bat progresses), or swing from the heels early in the at-bat (knowing that’s when they’re likely to see the best pitch to crush). The most effective way to address the overabundance of home runs might be to modify the composition of the baseball itself
  • Probably reduce strikeouts. More at-bats will end early, so this will reduce strikeouts overall. However, if you break it down to strikeouts after the count reaches two strikes, the strikeout rate in this particular category will probably increase (but so what? If true, this would place greater importance on batters to prevent the count from reaching two strikes – that’s a good thing!)

I think this concept has promise to introduce all sorts of cool strategy, which I think fans would enjoy. Also, currently, most fans (including myself) essentially just want to see the outcome of the at-bat (there’s a little, but not much, interest in the pitch-by-pitch path that an at-bat takes to reach its outcome). I think the dynamic strike zone concept could add a significant amount of interest in the pitch-by-pitch path that an at-bat takes to reach its outcome (fans of the batter’s team licking their chops early in the at-bat, and fans of the pitcher’s team breathing a huge sigh of relief if he gets past that first perilous strike, to ultimately seeing fans of the pitcher’s team licking their chops late in the at-bat, and fans of the batter’s team crossing their fingers late in the at-bat – more so than they already do for a very tangible reason).

As it stands, I could take or leave the ever-present strike zone graphic on TV (it’s okay I guess), but the dynamic strike zone concept could make it much cooler – fans watching at home can see the strike zone expand before their eyes as the at-bat progresses.

Overall, I think this concept could appeal to casual fans and purists alike.

  • Other thoughts?
    • Over the years, baseball’s harshest critics and biggest fans have rolled their eyes (and understandably so) about the uncertainty of the strike zone. If you ask X people on the street (even those knowledgeable about baseball) what the boundaries of the strike zone are, you’re likely to get X different answers. WHAT IF THE FUZZINESS SURROUNDING BASEBALL’S STRIKE ZONE BOUNDARIES – SEEN AS SILLY FOR SO LONG – ULTIMATELY TURNED OUT TO BE BASEBALL’S SALVATION? If strike zone boundaries instead were super-ingrained all along, it would make the dynamic strike zone concept a tougher sell. This longstanding fuzziness might help the concept gain acceptance.
    • If the dynamic strike zone concept is possible at all (in other words, if capable technology exists), and if it’s effective at all, then MLB can take the concept to still higher levels of effectiveness in the years to follow, by tinkering as necessary with the three strike zones to produce the optimal effects
      • Are batters crushing the ball like a video game with no strikes? Okay, let’s expand the 0-Strike Zone a little
      • Are batters taking too many pitches with one strike already on them? Okay, let’s find a way to widen the disparity a little between the size of the 1-Strike Zone and the 2-Strike Zone
      • Is the concept increasing hits and overall balls in play to a more palatable level, but with too many home runs? Okay, let’s keep the respective dynamic strike zones the same size, but let’s shift them all downward a few inches (or de-juice the baseball)
      • Etc.
    • The spirit of the dynamic strike zone is that it offers a tangible incentive for batters to put the ball in play early in the count (and a corresponding disincentive for working deep counts). Other ideas could also be considered (whether they have anything to do with the strike zone or not) if they are founded on the same principle
    • But wait a minute. If MLB stands to benefit by shortening the average length of plate appearances, isn’t there an easier way to do it? Why not leave the strike zone alone and just start all at-bats with a 1-1 count?
      • Starting all at-bats with a 1-1 count would surely shorten the average length of plate appearances. However, it would also surely increase the percentage of plate appearances that end with a strikeout or walk, when there is already an overabundance of such plate appearances as it is. The dynamic strike zone would likely shorten the average length of plate appearances and decrease the percentage of plate appearances that end with a strikeout or walk


  • Further Discussion about the Dynamic Strike Zone’s Effect on Average Pitches-Per-Plate Appearance
    *What you read below is heavy on speculation! I wouldn’t dare call it research* 

I’m very confident the dynamic strike zone would reduce pitches per plate appearance. Pitchers would feel more urgency not to fall behind early in the count (falling behind early in the count is bad news now – imagine falling behind 2-0 and still having to throw a pitch into a tiny strike zone. Danger!) More importantly, hitters would never again approach a plate appearance with the mindset of working a deep count (think about that!), and would no longer be willing to casually take a strike here or there, because they know (based on a tangible reason – the size of the strike zone) that the best pitch of the at-bat is likely to come early in the count.

Currently, the average plate appearance lasts about four pitches (https://www.beyondtheboxscore.com/2017/6/8/15740868/pitches-per-plate-appearance-runs-created-offense-zone-rate). Given that teams average about 38 plate appearances per game (https://www.sportingcharts.com/mlb/stats/team-plate-appearances-per-game/2015/), meaning teams combine for about 76 plate appearances per full nine-inning game, the average MLB game currently includes about 304 pitches per game.

How much would a dynamic strike zone reduce pitches per plate appearance? I dunno, but let’s just guess that it could knock that down to three pitches per plate appearance (which would return the sport to pre-1988 levels, when this statistic was first tracked). Maybe that type of decrease is unrealistic, maybe it’s perfectly reasonable, maybe it actually undersells the effect of the dynamic strike zone, who knows…

If accurate, the quick math (not necessarily factoring in all related effects) points to a reduction in overall pitches per game from 304 to roughly 228 (~76 * 3), which would lead to a significant reduction in overall length of game (by cutting out about 76 pitches).

But it gets better –  let’s first define an action pitch to mean the final pitch of any plate appearance – the pitch that determines/reveals the outcome of a plate appearance (so, with about 76 total plate appearances per game, we see 76 action pitches per game; the other pitches are just filler); the 76 pitches cut out of games would all be filler pitches!

I actually think the dynamic strike zone would boost offense, which would directly increase the number of plate appearances per game, and would add some of those pitches back into the tally. I won’t speculate any further about how many additional plate appearances we would see, but I think it’s very possible that the dynamic strike zone could provide ALL of the following to Major League Baseball: reduced length of game, increased rate of balls in play (and the corresponding decrease in strikeouts and walks), and increased offensive output (and, as a bonus, reduced pitcher injuries based on a reduction in overall pitches?)