UTK 1/20/26

Doing The Defense

Juan Soto gave an interview recently that included a quote that stuck with me longer than it probably should have:

“Defense is going to become a cornerstone of my development in the coming years. People think there’s nothing left to do, but the pride of a true baseball player is to keep showing something new, something different, in comparison to the rest.”

When my pal Jon Kiersky texted it to me, I joked back that maybe Soto had “found the Driveline of defense.” It was a throwaway line. But the more I thought about it, the less funny it seemed. Pitching has a Driveline. Hitting has half a dozen of them now. Why doesn’t defense?

For the last decade, player development has been driven by measurement. Pitch design turned feel into physics. Hitting instruction moved from “stay back” to bat speed, attack angle, and swing decisions. Entire industries formed around motion capture, force plates, and high-speed cameras. Injuries dropped in some areas, performance spiked in others, and careers were rebuilt on data that simply didn’t exist before.

Defense, meanwhile, is still largely coached like it’s 1998.

That’s not to say teams don’t track defense. They do, aggressively. Outs Above Average, Defensive Runs Saved, jump metrics, route efficiency, exchange times. Front offices can tell you precisely how many runs a player saves or costs. What’s missing is the translation layer. Pitchers get feedback loops. Hitters get drills engineered to change specific variables. Defenders mostly get video, positioning cards, and vague directives like “better first step” or “clean it up.”

Those aren’t development plans. They’re evaluations after the fact, though this has gotten better since we could actually measure the components like positioning, reaction time, speed/quickness, route efficiency, and more.

Imagine what a true defensive lab would look like. Start with movement, not outcomes. First-step explosiveness measured with apps and cameras. Lateral acceleration broken down the same way sprint coaches analyze starts. Route efficiency trained with constraints, not just reviewed on film. Arm strength is easy to quantify; arm accuracy, release consistency, and decision latency are not, but they’re absolutely measurable with modern tracking.

Now layer in cognition. Defensive value isn’t just physical. It’s anticipation, pattern recognition, and decision speed under uncertainty. We already know reaction time degrades under fatigue and stress. We know visual occlusion training improves pitch recognition. Why wouldn’t similar tools apply to reads off the bat, or infield hops, or cutoff decisions? Defense is a perception-action loop. That’s a solvable problem.

The biggest reason this hasn’t happened yet is incentive structure. Pitching and hitting are paid first. Defensive gains are marginal compared to adding five homers or half a mile per hour of velocity. But marginal gains add up, especially when they’re durable. A hitter can slump. A pitcher can lose a tick. Defensive improvements, once ingrained, tend to stick. Aging curves suggest defense often declines earlier, but that may be because we’ve never truly trained it.

Soto’s quote hints at something important. Elite players eventually run out of obvious improvements. At that point, longevity and durability are often the differentiators. Hall voters like counting stats. Defense is a place where stars can separate themselves quietly, extending value without changing who they are at the plate. It’s also an area where teams could unlock wins that don’t show up in exit velocity leaderboards.

We built labs to teach arms how to spin a baseball more efficiently. We built labs to teach hitters how to move a bat through space with intent. The field itself, 2.5 acres of chaos and reaction, is still coached mostly by feel.

Maybe Soto is right. Maybe there is something new left to show. The question isn’t whether defense can be trained scientifically. It’s why we’ve pretended for so long that it can’t. So if you’re out there and doing this, contact me. I’d love to learn more. If I just gave someone a business idea, cut a brother in maybe!

Actually, for subscribers, I did a deep dive to answer whether or not there’s any evidence this actually works. You should consider subscribing if you like this sort of stuff or if you’re really into injuries. I’ll do it like this all season.