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What will a shrunken strike zone mean for Oakland A's run prevention?

This was probably called a ball.
This was probably called a ball.
Neville E. Guard-USA TODAY Sports

Recently, news came out that baseball plans to implement key rule changes as early as next season. First, the league plans to change its increasingly gigantic strike zone by cutting the bottom of the zone. As it stands, the zone extends to the bottom of the kneecap. Over the years, umpires have extended that definition, calling more and more strikes below the kneecap. Changing the ruling is an attempt to curtail those extra strikes and increase offense.

In addition to the strike zone, baseball will make intentional walks automatic. Instead of lobbing four awkward tosses to the catcher, pitchers and managers can purposefully put a guy on first with a simple hand movement in an attempt to speed up pace of play. Not much to take away from this, although if there's a baseball team that would lose game botching an intentional walk, it's your Oakland Athletics.

How will the strike zone change affect the A's?


Let's start with the obvious. A smaller strike zone can lead to more balls and thus more walks, if a pitcher has subpar control. It would stand to reason that a smaller zone is worse for teams with worse control.

How have the A's done so far in the control department? Not so bad.

Total walks Rank BB% Rank
107 5th 9.40% 6th

That number only includes starters, since relievers are combustible roulette tables. That's a little inexact though, we can do better. Let's look at the four guys under contract for next year: Sonny Gray, Sean Manaea, Jesse Hahn, and Kendall Graveman should be in the rotation to start. How have they fared so far this season?

Pitcher BB% League Avg. Difference
Sonny Gray 10.80% 8.40% 2.40%
Sean Manaea 6.90% 8.40% -1.50%
Jesse Hahn 6.90% 8.40% -1.50%
Kendall Graveman 9% 8.40% 0.60%

I'm not satisfied with that as a great measure of control, but we can at least know the A's shouldn't just have their collective walk rates skyrocket. That could change, especially if our starters continue to be punished when keeping the ball in the zone, but at least they have the capacity to throw strikes.

Beyond control, a smaller zone, cut at the bottom will affect pitchers who live and die by spotting pitches near the knees. Specifically, sinkerballers will be affected more, at least in theory.

As umpires cease calling the low strike, hitters will chase balls below the zone less frequently. Pitchers will be required to live in a more hitting friendly location, something that will likely affect pitchers who don't have stuff to work up in the zone most.

That's all theoretical, of course, but making hitters chase pitchers at the bottom of the zone is at least somewhat predicated on the fear of called strikes. Take those away, and it's a whole different ball game.

Unfortunately for the A's, their rotation is chalk full of sinkerballers. Will a raised zone mean disaster?

Here's a breakdown of how frequently the A's throw sinkers, two seamers, and cutters. Sinkers and two seamers are often classified differently but typically move in a similar manner. Cutters move in the opposite horizontal direction than two seamers/sinker, but still elicit vertical drop.

Sinker % Rank Two Seam % Rank Cutter % Rank
11.80% 11 12.10% 20 6.40% 10th

More specifically, let's look at the supposed core four of Gray, Graveman, Hahn, and Manaea.

Pitcher Sinker % Two Seam % Cutter %
Sonny Gray 0% 19.90% 2.90%
Sean Manaea 0% 0% 0%
Jesse Hahn 0% 58.20% 0%
Kendall Graveman 41% 0% 30.80%

One of Manaea's supposed strong suits, provided a healthy arm, is the rise on his fastball. Therefore, the lowered strike zone probably affect him like it will others, though his control probably isn't the best bet going forward. We haven't seen the electric fastball we've been promised by Manaea, but if he has it, he'll probably be a better pitcher up in the zone.

A healthy and slider-using Gray will probably be relatively unaffected by a differing zone, too. His success below the zone is mostly due to his (now missing) slider, a whiff generating filthball that tempts hitters even when it falls a yard short of the plate. He certainly has had some success low in the zone or below with his sinker, but it's not a cornerstone of his arsenal. That's all predicated on his ability to return to form, of course.

Jesse Hahn and Kendall Graveman are a little different. Both rely on tail and sink heavily, and neither has the fastball to live up in the zone like Gray or Manaea.


Hahn seems to have some bad luck getting calls low in the zone and below, especially with his sinker. Part of this is probably due to some poor pitch framing (spoiler alert) but at any rate, a slightly raised zone wouldn't be anything new for Hahn going forward. The question becomes, will his bad luck with strike calls carry over to proposed strike zone, or will he fall more in line with the rest of the league?

Hahn hasn't exactly been successful down in the zone. Where you'd expect groundballs, Hahn has induced linedrives.

Hahn linedrive

That's probably a reflection of his status as a work in progress, but he's seen success before, and it's not totally predicated at succeeding low in or below the zone. Still, a sinkerballer will see success most down in the zone, and news of the zone change probably didn't elicit a happy dance from Hahn.

Kendall Graveman

Like Gray, a rule change is the least of Graveman's worries at this juncture. He's looked out of sorts lately, nibbling like your dieting coworker at lunch and looking generally uncomfortable on the mound. Reading into his results when he's been such a bipolar pitcher for the first year and change of his career won't provide us with clear answers, but can give us a general idea of what the zone change will mean.

What do we know about Graveman now? He lives below the zone and dies in its center. He's not getting called strikes below the zone like more established guys are, so Graveman won't be required a huge change going forward.

Still, he's a groundball guy who primarily gets groundballs when he works down.

Graveman groundball rates

If hitters are forced to swing less and Graveman is forced to work up more, it could spell disaster. Lower zones are certainly better for Graveman and his downward movement is complemented by strikes called low in the zone.

Of course, Graveman's current struggles have everything to do with harnessing his stuff. If he does that, a strike zone change would be less a major issue.


Like pitching, the effect of a strike zone change on catching isn't a clear thing. We do have data on catcher's receiving abilities, and the A's don't grade out well.

zBall% refers to pitches that were strikes per pitchF/X but were called a ball by the umpire, oStrike% refers to pitches caught outside the zone that were called a strike by the umpire. The former typically means it's poorly framed by the catcher, that the umpire didn't call it a strike because of the catcher. The latter is indicative of good framing skills.

Catcher zBall% Rank oStrike% Rank
Stephen Vogt 18% 4th 6.70% 42nd
Josh Phegley 14.30% 31st 7% 34th

The A's high rankings in strikes called balls and low rankings in balls called strikes means the A's catchers aren't good at framing, rarely convincing umpires a call should go in Oakland's favor.

The effect of a changed strike zone on framing isn't clear. Umps have shown the ability to adjust, and there's a chance framing will have a lessened effect as the zone shrinks. I'd bet that a smaller zone will put an increased importance on framing: as strikes become more rare, their value will increase meaning a catcher's ability to earn borderline calls will be more valuable.

What does it all mean?

Of course, everything here is theoretical and subject to adjustments. Maybe the change in strikezone will be imperceptible, maybe A's pitchers will generate more success up in the zone. It does seem like a zone change would affect pitcher's relying on vertical drop more and teams with better framing skills less. As it stands, the A's are on the wrong side of both of those equations, but 2017 is a long way away, and the A's aren't typically a group that stands pat.

More than that, the rotation is more in flux now than it has been in recent memory. A 2017 strike zone change is the least of the A's pitching worries. Pick up the pieces, fix what's broken, and deal with a potential new obstacle when the time comes. But, a shrunken strike zone doesn't seem ideal for a team with major pitching woes and poor receivers, especially one like the A's.