Who Should Join the (Oppo) Groundball Revolution?
To begin this article, here’s a statistic. It’s the league-wide rate of shifts, as defined by Baseball Savant, by year:
- 2016: 13.7%
- 2017: 12.1%
- 2018: 17.4%
- 2019: 25.6%
- 2020: 34.1%
Since it was first tracked in 2016, the league-wide rate of shifts has nearly tripled. That’s because, well, shifts work. Batted ball wOBA from 2016 to 2020 has remained stagnant, while pulled grounders — what shifts attempt to gobble up — have steadily decreased in value. The drawback, if any, is minimal.
You could, however, view this as a negative development. There’s a case to be made that by limiting the amount of balls put into play, shifts are encouraging the pursuit of three true outcomes: walks, home runs, strikeouts. Does that create a more boring game? I don’t know, but lots of people think so. There have been calls to ban the shift altogether, or at least introduce restrictions on how teams can align their infield defense.
The debate aside, the prevalence of shifts has introduced an inefficiency. Pulled grounders have decreased in value, but as new holes opened up in the infield, the value of opposite-field grounders has increased:
In previous years, maybe there wasn’t much incentive to go the other way. But consider the wider-than-ever gap between the two grounders in 2020, when pulled ones averaged just .174 wOBA, while opposite-field ones averaged .376 wOBA — a difference of .202 wOBA. When shifts were least used in 2017, the difference between the two grounders was .119 wOBA. An upgrade from .119 wOBA to .202 wOBA is quite significant; that’s roughly the distance between Mike Trout’s wOBA (.407) and Ramón Laureano’s wOBA (.315) in 2020.
Rays’ infielder Yandy Díaz took advantage of this trend last season. Although his average exit velocity and launch angle plummeted, he managed to record a career-high 138 wRC+ by hitting ground balls the opposite way — his GB% and Oppo% soared to 60.0% and 42.3%, respectively. “Pitchers and Fielders Hate This Hitter’s One Trick!”, a clickbait-y version of this article would proclaim.
However, the benefit of going the opposite way is limited to ground balls. During the same timeframe (2016–2020), pulled line drives and fly balls outperformed their opposite-field counterparts by a significant margin. There’s also more variance involved, as ground balls are subject to the fickleness of BABIP regardless of their direction. Not to mention that this approach requires consistent contact, whereas elevating-and-celebrating lets hitters get away with a few extra swings-and-misses.
Indeed, it’s not for everyone. But for hitters who possess the required skills, defying the shift could absolutely give a boost to their offensive output.
Here’s an idea: What if we find hitters who can benefit from the (oppo) groundball revolution? I looked for the following traits: (1) a high rate of pulled ground balls, (2) a high shift rate, (3) above-average Contact and Whiff rates, and (4) an average-ish output by wRC+. That last requirement is there because there’s no point in changing an already elite hitter — we want improvements, not unnecessary tinkering.
Based on the criteria, here are five hitters worth looking into:
- Cavan Biggio — his current approach seems acceptable, as shown by the 119 wRC+ he’s put up so far. But there are several red flags. Although he does elevate the ball often enough, it’s when he doesn’t that is troublesome. Biggio hits grounders to the pull side a whopping 72.4% of the time, allowing teams to set up shifts in nearly two-thirds of his plate appearances. His average EV and barrel rate also crashed in 2020. If they don’t rebound soon, Biggio might succumb to the shift. But due to his youth and talent, he’s who I am least worried about.
- Tommy La Stella — a great hitter with fantastic plate discipline to boot. So why is he on this list? It’s because teams are increasingly willing to shift against him. They shifted in just 9.5% of La Stella’s plate appearances in 2018, but that rate has skyrocketed to 46.5% in 2020. It’s an issue because the shift seems sap his offensive output — quite dramatically. Along with Cavan Biggio, he had one of the worst wOBA differentials between his shift and no-shift PAs in 2020:
- Asdrúbal Cabrera — a consistent contributor for years who doesn’t get enough recognition. Age has caught up to him, however, and for the past two years he’s hovered below 100 wRC+. Can going the opposite way deliver a jolt to his career? He still makes consistent contact whilst minimizing whiffs, and to my surprise, mustered an above-average exit velocity of 89.5 mph in the shortened season (64th percentile). His being a switch hitter makes does complicate things — teams rarely shift against him when he bats Right — but man, just imagine this happening more often:
- Jurickson Profar — he doesn’t get shifted that often compared to others on this list, but he’s someone who would absolutely benefit from going the Yandy Díaz route. Part of his struggles at the plate are explained by middling batted ball data. After years of trial-and-error, it’s clear Profar is incapable of hitting a baseball very hard. But maybe he doesn’t have to! As Díaz has shown, choosing the opposite direction requires less exit velocity for one to succeed. Besides, there’s not much to lose for Profar if a change of approach fails, and a lot to gain if it does succeed.
- Todd Frazier — I almost didn’t include him on this list due to his relatively poor whiff rate and batted ball numbers, but two facts stuck out to me. The first is that his Cent% — the rate of balls he sent up the middle — increased from 32.0% in 2019 to 40.9% to 2020, which might have been an effort to escape his slump. It didn’t work, but what if he channeled that energy into going the other way? The second reason is more sentimental. It saddens me to see a once-solid hitter gradually decline each year, and I would love Frazier to experience a renaissance.
So, how does one go the other way? Again, we can take a page from Yandy Diaz’s book. In observing his swing, it’s easy to notice when he’s pulling the ball and when he’s intending to go the other way. Here’s a comparison between an at-bat from 2019 (on the left) and one from 2020 (on the right):
The two images were captured at the moment of contact. What, then, is the difference? In the left image, Díaz’s torso is rotated outward and his wrists are cocked forward, allowing him to yank the ball. In contrast, Díaz assumes more of a closed, less forward stance in the right image, with his wrists cocked back. This allows him to drag the ball with the barrel and send it to the opposite field:
This isn’t the perfect analysis –– the velocity and location of both pitches differ, though I tried my best to keep them as similar as possible –– but it works, and it shows that the steps required to go the other way are clearly defined.
A question I can’t answer, however, is whether becoming proficient at doing so is possible within a single offseason. Dragging the ball rather than pulling it can be difficult, leading to weak contact and foul balls if executed without enough precision. Still, as always, Díaz provides a blueprint as well as hope. If he could transform himself in between a season –– albeit with a longer offseason –– then there’s no reason to say other hitters can’t.
Who knows, maybe the (oppo) groundball revolution is just the solution to the shift-or-no-shift debacle. As more hitters poke balls into places teams don’t expect, the problem should fix itself. We can’t expect every hitter to change their approach, and they shouldn’t, but a small battalion of Díaz-like hitters striving to become better might be enough.
All data courtesy of Baseball Savant and FanGraphs.
