In the cat and mouse game that is the postseason, every decision matters, regardless of how big or small. If a marginal competitive advantage can be exploited, odds are a team will take their chance. Last year, I investigated what I thought was a key reason for the Astros’ postseason success over the last decade. The piece explored swing path diversity and how Houston had more of it than any other team from 2021 to 2022. Constructing a balanced, dynamic lineup is one of the tools teams can use to keep pitchers and opposing managers honest. There are multiple ways to define balance in a lineup, including swing aggression, whiff tendencies, speed and athleticism, and handedness. But that piece focused on variance in Vertical Bat Angle (VBA) within lineups.

If you aren’t familiar with VBA, it’s the vertical orientation of the bat at contact, where 45 degrees is a diagonal bat. It is pitch height dependent – the number goes down as height increases (flatter bat) and goes up as height decreases (steeper bat), making it vary within a player’s own swing profile. There is also variance player to player. On average, Aaron Judge and Freddie Freeman have much steeper barrels at impact than flatter-swinging hitters like Juan Soto and Randy Arozarena. VBA is one of multiple important bat tracking metrics — horizontal bat angle, point of contact, bat speed, acceleration, and time to contact are a few others — but VBA is the most easily accessible due to the computer vision work done at SwingGraphs.

Because of this accessibility, VBA has been my go-to proxy for tracking bat path changes on a player-specific level. Bat path has a strongest causal effect on whether or not a player is a good hitter, but it also impacts how pitchers determine sequencing and pitch selection. With that said, let’s investigate swing diversity among the playoff lineups, and in particular, those of the Texas Rangers and Arizona Diamondbacks.

To begin, I took a slightly different approach to preprocessing my data this time. As I mentioned, handedness plays a big role here because it’s a key factor in how managers stagger their lineups. Two hitters can have the same VBA, but if they are of the opposite handedness, their path is different. To account for that, I took the inverse of all left-handed hitter’s VBA. Similarly, I wanted to account for switch-hitters. 72.2% of switch-hitter plate appearances came against right-handed pitchers in 2023. So instead of taking the inverse, I multiplied all switch-hitters’ VBAs by -.722. Think about it as them being a lefty 72.2% of the time.

In terms of who was in or out of the dataset, I only included hitters on postseason rosters with at least one plate appearance. That really only significantly affected the Rays, who were without Luke Raley and Brandon Lowe. Lastly, I only used VBA from the September/October portion of the regular season. My logic was that what a hitter looks like in April can be different from September. Hitters go through swing fluctuations, and I wanted to have the most recent representation of their swings. For the calculation, variance is still the measure used to represent diversity, but I’ve adjusted the number to be a percentage above or below average (of playoff teams only), with the average set at 100, as with wRC+, OPS+, etc. With that said, I present VBAVar+ for playoff teams in 2023:

For two postseasons in a row, the Phillies have been the most productive NL offense by wRC+. This year, their team-wide 118 wRC+ was very good, a full 19 points higher than their NLCS opponent, the Diamondbacks. The team doesn’t have any switch-hitters, but on both the left- and right-hand side, they have over 10 degrees of dispersion. Trea Turner (29.0 degrees) has the flattest swing on average among right-handed hitters, while Nick Castellanos (40.5) has the steepest. Brandon Marsh (41.6) has the steepest on the team, and Kyle Schwarber is 0.8 degrees above Turner, making him the flattest lefty. There is a wide variance of swing path in this lineup, and the Turner addition added a layer of diversity that the 2022 team didn’t have. From a game planning perspective, that diversity is a nightmare in a postseason matchup.

Similarly, the Twins and Dodgers have variance at least 10% above average. The Twins platoon strategy significantly impacts this, but they also have hitters as steep as Edouard Julien (42.1) and as flat as Royce Lewis (25.8). Both are on the extreme ends across the entire league, not just their own team. On the Dodgers’ side, Freeman is also high at 42.0 degrees, and is balanced by flatter swingers like Jason Heyward (27.6), David Peralta (28.8), and Enrique Hernández (28.1).

As for the Astros, my piece last year crowned them the team with the most swing path diversity, so what gives? Well, there has been a bit of convergence in their VBAs compared to the previous two seasons. Yordan Alvarez and Kyle Tucker’s swings converged closer to one another after being on opposite sides of the spectrum. Chas McCormick’s swing flattened significantly in the final month after being almost perfectly diagonal for most of the season (and last year). Swapping their first baseman from the extremely flat swinging Yuli Gurriel to a middle-of-the-pack swinger like José Abreu also brought them closer to the average. To be clear, these are still fantastic hitters, but the convergence hurt the advantage they had built up in years past.

Let’s now shift to the most relevant part of this conversation: the World Series matchup. The Diamondbacks and Rangers may not have the same level of swing path diversity as other clubs, but there are aspects to each team that make for interesting decisions by Bruce Bochy and Torey Lovullo.

The Diamondbacks 97.98 VBAVar+ mark is average, but there is good balance here from a handedness perspective. They run out two lefties and two switch-hitters every day, then have a group of solid right-handed hitters. The limitation is that both of their lefties have extremely flat swings. Corbin Carroll (28.3) and Alek Thomas (24.9) are on the shorter side, so that makes sense. However, Lovullo has been very strategic in who follows those two in the lineup. Gabriel Moreno’s bat path steepened as his health improved and made its way to an above-average mark at 37.6 degrees. Following up a flat swinging lefty like Carroll with a more loopy hitter like Moreno (even if they’re separated by one hitter against right-handed pitchers) forces a pitcher to change their pitch selection. Nathan Eovaldi doesn’t significantly partition his pitch mix, but he’ll have to change how he uses his four-seamer against each of these hitters when they face off tonight. And plus, Ketel Marte will likely be sandwiched between those two and he has been on absolute tear.

Eovaldi will face a similar issue when the Thomas-Lourdes Gurriel Jr. part of the lineup comes up too. Gurriel’s VBA comes in at 34.9 degrees; he had good success against changeups and splitters this season and wasn’t great against heaters. This will likely mean Eovaldi takes a fastball-heavy approach against the left fielder. However, if Thomas follows him in the lineup like he has previously, Eovaldi will have to immediately pivot his approach because of Thomas’ success against four-seamers this year. He hit .309 against them with a .384 xwOBA. It would be ideal if Eovaldi could immediately get in a rhythm with his splitter, but he’ll be forced to mix things up with this part of the lineup. However, it’s not all bad news for him. Tommy Pham and Christian Walker have less than a degree of VBA separation between them and are likely to hit behind one another. This will be an opportunity for Eovaldi to use a similar pitch mix and especially lean on his splitter since these two hitters haven’t had much success against offspeed pitches.

On to the Rangers’ side of things, Zac Gallen will be forced to rotate handedness all night except against Corey Seager and Evan Carter. That’s not much of a break! The two are separated in VBA by over 1.5 degrees, and Seager is a breaking ball killer. Due to its vertical orientation, Gallen’s best pitch against lefties is his knuckle curve, but Seager slugged .686 against right-handed curveballs this year. His knack for creating lift on low pitches by adjusting his body is bad news for Gallen. After Seager and Carter, he’ll then have to manage Adolis García, who just continues swatting homers.

But the more interesting part of this lineup from a VBA perspective comes when Leody Taveras and Josh Jung step to the plate. Taveras has a flatter swing; his VBA is at 29.6 degrees. He maintains a taller posture throughout his swing and doesn’t make any significant barrel adjustments. This will be an advantage for Gallen because he can use his knuckle curve and changeup to move under Taveras’ barrel. In other words, it will be about keeping the ball down against Taveras. The issue is that the same zones that are Taveras’ weaknesses are actually Jung’s strengths. His loopier 36.9 degree VBA steepens even more on low-middle and low-in pitches. His xwOBA in those zones during the regular season were .468 and .515, respectively.

This is where staggering swing types can become an advantage. Going from an extreme weakness in one zone to an extreme strength back-to-back forces a pitcher to change his physical feel and pitch approach. Nothing is more difficult than needing to execute multiple game plans on a rotating basis. But if Gallen is looking for something to lean on, it’s that he can take a similar approach against the flatter swinging lefties like Heim, Taveras, and Nathaniel Lowe. Since there isn’t much diversity among those three, he may have an easier time getting in a rhythm in the bottom half of the lineup. The key will be staying away from Jung’s hot zones and not letting Mitch Garver cheat on the four-seamer since that was the pitch he ambushed so well against righties this year (.510 xwOBA).

As you watch this weekend’s games, pay attention to these matchups, especially how each pitcher is forced to change their pitch selection depending on swing paths. These teams may not be as widely dispersed as others in the playoff field in terms of pure VBA variance, but there are lanes in each lineup that will force pitchers to dynamically execute different game plans, something that is much easier said than done.