To swing or not to swing, that is thee question
With the tying run on third base in the ninth inning, two outs, and the count full in the World Baseball Classic semifinal meeting last month, Geraldo Perdomo watched a wicked Mason Miller slider break well below the strike zone.
The offering should have been called ball four. Fernando Tatís should have come to the plate with runners on the corners and an opportunity to advance to the Dominican Republic to the final. But this is a game played, and umpired, by humans.
Home plate umpire Cory Blaser called a strike. Team USA celebrated. Perdomo froze in shock.
Given the leverage of the moment, it was the most costly missed call of the tournament. It was a true binary, survive-or-die, game-ending errant call, if only we had ABS technology in the WBC this spring.
As the game ended, a new debate immediately began: To swing or not to swing? Did Perdomo make the correct swing decision?
There are those who believe he ought to have been protecting with two strikes, expanding his zone to attempt and cover a large halo around the strike zone.
Did Perdomo make the right decision? It is a question worth exploring to understand probabilistic decision-making hitters are tasked with making – and doing so in milliseconds. It also raises another question: how can we help train and coach players to make better decisions and hone approaches? After all, the strike zone is the most important real estate on the field for batters as well as pitchers.
Let us begin with what Driveline’s swing decision model had to say about the decision.
It graded Perdomo’s decision as an elite decision.
That might be difficult for some to accept, but we live in a world of probability, not certainty. There will occasionally be suboptimal outcomes as byproducts of good processes. Driveline’s Jack Lambert explained the model’s logic and accounting on X:
“Sixty percent chance of swing, 40% chance of take,” Lambert wrote of the situation. “If no swing: 0.5% chance of (a called strike). If a swing, 63% chance of a whiff.”
The math was on Perdomo’s side in not taking a hack.
That pitch location is very rarely called a strike.
And even if Perdomo swung, it’s about impossible to do much damage to a Miller offering located below the zone – let alone contact it.
When examining the probabilities associated with swinging versus non-swinging in this situation not seemingly much room for debate.
(Our model is trained on MLB data, so it does not take into account WBC umpiring but Blaser is a MLB umpire).
While coaches often talk about “protecting with two strikes,” our model can help
inform batters of where their decision making might be errant and perhaps have them learn to think more probabilistically.
Professional player, and hobbyist data analyst, Robert Stock shared similar logic in thinking through a decision tree on X:
“A huge misunderstanding that people have is that an MLB batter should be protecting against every (two-strike) pitch that could possibly be called a strike. An MLB batter shouldn’t even be protecting against all actual strikes. To do so would mean increasing your chase rates to an absurdly high level. And the likelihood a batter has a positive result (foul ball or a hit) on a perfectly executed two strike pitch is very low. Couple these two facts together, and anyone arguing otherwise means one of two things – you genuinely didn’t know this until now or you have an idea floating around your head that doesn’t match reality.”
And if pro batters shouldn’t be protecting against two-strike pitches well off the plate, many amateur players should not either.
How do we think about swing decisions in our training of hitters at Driveline?
I asked Driveline lead hitting instructor Tanner Stokey about the Perdomo debate.
“On paper – on paper – (Perdomo) made the right decision. It was a ball,” Stokey said. “But the one thing for me – it’s based off the game state, the game situation – is it’s really difficult to stomach leaving the outcome of the game in the umpire’s hands. I think it was the right decision. It was a ball. But generally, I’d be pushing there to swing on the edges right there. Realistically, though, the chances of anything productive happening on that.”
This is where art starts to creep into science.
While trying to protect six inches off the plate against a Miller slider is a low expected value decision, hitters do want to be adaptable to different game states.
Hitters can benefit from the ability to expand and spoil a pitch that is an inch or two off the plate, a pitch residing in the shadow zone. The ability to fight another day, to survive to the next pitch. (The Perdomo pitch was below the shadow zone.)
Thinking about the quality of swing decisions is further complicated as Stokey notes that not all strikes are “created equal,” especially early in the count.
“I look at swing decisions differently than I look at an approach,” Stokey said. “Swing decisions in terms of models, they are just essentially grading your decision to swing or take a given pitch.”
Models do not capture all considerations, everything that matters in the calculus of an approach.
A hitter’s approach must consider game state, count leverage, and a hitter’s specific strengths, to understand when a batter should zero in on a location, and when he should expand. Our data-based tools – and training programs – can help hitters understand how to optimize their approaches.
“Especially early in the count, it’s incredibly important that you are playing offense and you’re not taking defensive, reactionary, passive swings,” Stokey said. “Early in the count, if you’re going to swing at a pitch down-and-away on the black – the chances of you doing something productive there is slim, right? Even though it’s a strike, and it’s going to put you further behind in the count, the chances of you doing something productive with that swing are not very high.
“Now, on the flip side of that, (a hitter) should damn near 100% of the time be swinging at pitches in the heart of the plate because that’s where most production happens.”
I once asked Joey Votto about how he equated the process of getting the pitch he wanted to hit as something akin to boxing.
“It’s like a boxer who is always trying to lead the guy into his straight. You have to manipulate him with your footwork. Same type of thing in baseball,” Votto said. “You have to figure out a way to funnel [the pitcher] into your hot zone. That comes with patience and that comes with accepting or realizing there will be some error on their side.
“It’s almost like as a hitter you have to be a counter puncher. The best way to be a counter puncher is just to sit and wait and absorb and then counter with whatever you think your strength is.”
Perhaps the focus on the swing-or-to-not-swing question regarding Perdomo should not have been tied to the full count pitch but, rather, the third pitch of the at bat when Perdomo watched a fastball split the center of the plate.
Granted that offering was 100.7 mph out of Miller’s hand – not the easiest pitch to turn around – but by not swinging at a center-cut fastball, the count leverage went from neutral to a 1-2 count, and severely in favor of Miller. That was also his best pitch to hit.
Hitters should all be more aggressive when they have leverage but they also ought to have individualized approaches.
For instance, Aaron Judge and Luis Arráez ought to have much different approaches.
“If you take Judge versus Arráez and they swing at a slider on the black, down and away, the chances of an Arráez doing anything good with that pitch when he puts it in play is very slim,” Stokey said. “The chances of Judge doing something productive is significantly higher because he has so much bat speed, he has so much ability to create velocity and impact on baseball.
“Low-power guys should be even more selectively aggressive. When they are swinging early, they should really be leaning into getting that ‘A swing’ off. “
This was even an issue for Mookie Betts in working with Stokey back in 2023. Betts was too worried about making contact, and having the lowest K rate possible, and it was sapping his power. One aspect tied to his rebound season is he became more selective about when he swung. Betts added bat speed but there was also a mindset change, Stokey told me for this piece last fall.
“The thing with (Betts) was ‘Man, your bat-to-ball skills are so good,'” Stokey said. “A lot of times you see players with very good bat-to-ball skills, they don’t want to swing and miss. So, while Mookie didn’t have poor chase rates he would expand on the edges and swing on balls in the shadow zones and slow himself down for the sake of putting the ball in play. He’d slow himself down and make poor, unproductive contact.”
Even the best hitters in the game might not have quite the right mindset regarding where they belong on the power-contact spectrum.
The good news? There are ways to improve. But there is the question of training economy.
There are only so many hours in the day, only so many reps a hitter can take. How much of those should be geared toward a regime that focuses on decisions over, say, bat-speed training?
“If you want to look at it through the lens of the big three: power, contact, and swing decisions… good, a good training program, a good training environment, is going to take into account all those things,” Stokey said. “You can very easily train your power, your bat speed, and your contact skills, and your swing decisions in the same environment.
“Now, you need really awesome technology, like Trajekt, or you need a pitcher that can mix pitches to you in batting practice, things like that… Say a hitter gets a 50-50 (mix of pitches) off a Trajekt, or an iPitch something like that. (The athlete) is figuring out how to get their best swing off and make quality contact in an ‘A-swing’ situation, or finding a way to hit a line drive ball flight in a two-strike situation.”
A core principle of Driveline coaching is to embrace and create environments that force athletes to adapt through implicit learning.
For example, a specific two-strike protection drill is probably a suboptimal use of time, Stokey says. Rather, we want to create difficult, game-like environments.
Beginning this season in the majors, ABS technology will begin to protect a hitter like Perdomo from the unfortunate outcome of having made a correct decision in a high-leverage spot hurt by umpire error. Perhaps someday 99.9% of ball-strike calls will be made correctly. Perhaps one day the technology will trickle down to amateur games, too.
Still, even if rogue umpire calls decided fewer fates, the art and science of swing decisions and approaches will always be important.
Not all strikes are created equal. The optimal areas to attack differ for hitters. It’s a game of probability as Perdomo found out in the WBC. There is no certainty involving any one swing decision, but we want to place our athletes in a position to succeed as often as possible.
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