Best of BP: Quantifying the Corey Seager Approach

Picture credit score: Rob Schumacher-Arizona Republic

This text was initially revealed on November 8, 2023.

The Rangers are celebrating their first World Collection championship in franchise historical past for a lot of causes. Due to clutch showings from Nate Eovaldi and Jordan Montgomery all postseason lengthy. Due to well-timed sizzling streaks from seemingly the one two dependable arms in an in any other case shaky bullpen in Jose Leclerc and Josh Sborz. Due to clutch performances in lengthy aid from Jon Grey; the checklist goes on and on. Each champion has such a listing. However there will be no doubting the driving drive behind this Texas title: Their extremely deep and productive lineup, one which had no holes from leadoff hitter Marcus Semien to ninth hitter Leody Taveras. 

The lineup that stole essentially the most headlines through the common season performed at Truist Park in Atlanta, and it was pretty straightforward to level to what the Braves did nicely: 307 residence runs speaks for itself. Whereas Texas actually options hitters able to unbelievable energy—Corey Seager, Adolis Garcia, Mitch Garver, and Ezequiel Duran have been all within the high 20% of the league’s hitters in ninetieth percentile exit velocity, with Nathaniel Lowe not a lot additional behind—their lineup was in a position to grind away pitchers with greater than brute power. The lesson we will study from this 12 months’s champs is that when placing collectively a World Collection-winning lineup, it helps when practically each hitter on the roster possesses a sophisticated understanding of the zone, the depend, and tips on how to leverage these two issues collectively to get pitches they may do harm on. 

The interplay of these expertise materialize in generally tough to trace methods utilizing public metrics. A typical evaluation of a hitter’s plate self-discipline would start with their chase fee—or O-Swing proportion—which measures how usually they broaden the zone, aka swinging at pitches they shouldn’t. It’s essentially the most generally referenced metric for analyzing a hitter’s method; Juan Soto leads the league on this space 12 months after 12 months whereas Javier Baez charges among the many worst, as one may count on. The Rangers, relying on which website you’re utilizing, typically rated as one of the crucial disciplined groups by chase fee within the league. They have been fourth-best by PitchInfo, sixth by Statcast, and fifth in keeping with Sports activities Data Options (every website defines the boundaries of the strike zone in their very own method, which ends up in the variations between these metrics quantifying the identical factor). 

Chase proportion, for all its deserves, doesn’t inform the entire story. Regardless of a seemingly intuitive relationship with high quality of contact—pitches farther from the zone are tougher to place good wooden on—it doesn’t have a lot of a statistical relationship with any of the extra ubiquitous energy measures. For instance, with remoted slugging (ISO)—the distinction between a participant’s slugging proportion and batting common, successfully representing a participant’s “further base hits” talent—chase fee has a reasonably weak correlation (r of -.105 for 2020-2023). As an alternative, it has a a lot stronger relationship with a participant’s stroll fee (r of -.79 with BB%). It’s not measuring a hitter’s potential to acknowledge pitches they’ll hit, however as an alternative it quantifies a participant’s information of the zone. The talents are associated, however not the identical.

Take Corey Seager—now a two-time World Collection MVP, Seager has arguably the purest method within the recreation for a hitter. That’s mirrored not by his chase fee—that’s just about league common—however by his aggression on pitches within the zone relative to that chase fee. Seager is routinely among the many league leaders in zone swing (Z-Swing) fee minus chase fee (O-Swing)—in any other case often called Z-O Swing.

Whereas Seager’s Z-O Swing ratio clearly quantifies some distinctive talent that he seems to own, the addition of zone swing fee solely bumps the correlation to ISO to a .253 r. The development does trace at how we needs to be occupied with swing selections, although. The essential factor concerning the pitches that Seager swings at isn’t that they’re strikes. It’s that they’re hittable, no matter balls and strikes, due to their location. Letting a hittable pitch land within the zone usually results in worse outcomes down the street for a hitter. The important thing a part of making any choice is weighing up the advantages of an motion vs. the price of inaction. For Seager, that equation is simple: if he’s in a position to drive it then he hits it, and if he can’t then he doesn’t. He’s not ready for a selected pitch that will by no means come, however simply the primary one which he can harm. In that method he by no means cedes management of his at-bats to the pitcher. Pitchers can cover their fastballs from hitters who hunt them, however they’ll’t keep out of the zone altogether in the event that they need to keep within the recreation very lengthy.

With that in thoughts, I needed to measure the cost-benefit of every attainable choice a hitter could make in a method that might be extra statistically related than Z-O Swing. The fast and soiled of that course of: I checked out each pitch since 2020 and located the common run worth of a swing and a take at every mixture of depend and placement across the plate. I weighted every of these values by the likelihood of a referred to as strike, in order that the perimeters of the zone would mirror the 50/50 nature of these calls, then I discovered the distinction between the 2 to point out the entire “worth” that was up for grabs. Damaged out by swings and takes, that appears like this:

simply swings, we get this after we additional separate into the counts wherein the pitch was thrown:

What this reveals is that with two strikes, a hitter ought to at all times swing at something with a fairly excessive likelihood of being referred to as a strike, which makes intuitive sense. It additionally penalizes gamers with growing severity for swinging outdoors the zone after they’re about to be gifted a stroll, and rewards gamers for swinging at pitches within the coronary heart of the zone in practically any depend. Importantly, the penalty for being overly aggressive early in an at-bat is considerably smaller than it’s later in an at-bat, incentivizing early swings—inside motive—except a hitter can confidently deal with a two-strike depend.

Utilizing these deltas between the common values of a swing and a take, we will succinctly grade a participant’s swing selections by taking a look at whether or not they added or subtracted to their anticipated worth on every pitch.

Following the identical logic as Z-Swing minus O-Swing evaluating good selections to unhealthy ones, we’ll look first at an space wherein Corey Seager shines: not letting these hittable, high-value pitches by him. For our functions, which means taking a look at what number of of a participant’s taken pitches have been optimistic anticipated values, aka “hittable.” A decrease proportion is healthier right here, for the reason that thought is that deciding not to swing is popping down an opportunity to do harm. Amongst gamers with 200+ PA in 2023, listed here are the leaders (left, in blue) and laggards (proper, in orange) in Hittable Pitches Taken (as a proportion of whole takes):

Shock! Corey Seager sits atop the measure he impressed, letting fewer favorable pitches go unpunished than every other hitter. If it looks like a few of the different names on both aspect are seemingly misplaced for a plate expertise leaderboard, do not forget that this isn’t monitoring balls and strikes judgment: It’s taking a look at how opportunistic every hitter is. Mainly, this measures aggression when the hitter sees one thing they’ll do harm on.

On the opposite aspect of the spectrum, the hitters on the appropriate have been typically deemed too forgiving in the direction of pitchers—practically half the pitches Bryson Stott took have been probably hittable, which is smart when you consider his acknowledged plan of shedding excessive fastballs in 2023 and his consolation stage hitting with two strikes. That method largely labored out okay for him, however the implication right here is that he’s leaving harm on the desk by being overly passive.

If that measures aggression, now we’d like a proxy for choice. For that we’ll have a look at how most of the good selections a hitter makes that have been the results of not swinging at unhealthy pitches. That is their functionality or tendency in the direction of being selective. A better quantity is healthier right here; a low whole can point out unhealthy pitch recognition or a reckless method. Examine the leaders and laggards to see what I imply:

The hitters on the left are a few of the choosiest within the recreation, and in addition a few of the names we most affiliate with endurance. A lot of the gamers on the appropriate will be safely categorized as “free-swinging.”

The ultimate step is evaluating our two numbers. The distinction between these ratios offers us a “Z-O Swing-like” determine that represents how nicely a hitter balances opportunism with warning. Since he’s the patron saint of selective aggression (and since this produces a unit-less quantity that’s exhausting to explain), we’ll name this SEAGER: for SElective AGgression Engagement Charge. That leaderboard appears like this:

This new metric offers us an appraisal of how nicely a hitter stays on the entrance foot whereas retaining sufficient self-discipline to navigate the depend and finally settle for free passes to first base. It’s a little bit of an inelegant statistic as a result of—like Z-O Swing—it’s an interplay of ratios with completely different denominators, nevertheless it nonetheless bears a stronger relationship with key offensive statistics than each Z-O and chase fee have in each the current and in future seasons:

With out factoring in a hitter’s distinctive energy potential in any method—one thing I’ve tried to do earlier than, unsuccessfully—we’ve reached a weighted correlation of .41 with subsequent season ISO based mostly solely on a hitter’s swing selections. That’s fairly good! SEAGER is considerably much less dependable—that means correlated with itself—than each of the options (positively a disadvantage), however higher explains energy manufacturing within the brief and long run, which was the final word purpose right here. Mission completed.

Let’s do a fast recap earlier than we go:

Plate self-discipline is extra than simply drawing walks
What you swing at—hittable pitches—is extra essential than what you don’t—balls outdoors the zone—when the purpose is bettering high quality of contact
Balancing each is the most effective factor a hitter can do: that’s what SEAGER is
Corey Seager is wonderful
There’s extra work to be finished sooner or later, like seeing if this may be tailor-made to a hitter’s distinctive strengths and weaknesses each within the zone and when it comes to their energy potential. 

I’ll go away with this, which accommodates 2023’s SEAGER, Z-O Swing charges, and percentiles hooked up to every column. You’ll be able to see, for instance, that Jose Altuve went from a seventh percentile Z-O Swing fee to a 94th percentile displaying in SEAGER. Or that the Rays jumped from twenty third in Z-O Swing as a crew to sixth in keeping with SEAGER.