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Juan Soto’s discipline has carried his improvement

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Though how do we reconcile this with his increased groundball rate?

Miami Marlins v Washington Nationals - Game One Photo by Mitchell Layton/Getty Images

In just three seasons, Juan Soto has established himself as one of baseball’s most consistent hitters. But, this year, he’s also one of baseball’s most improved.

Into games on Wednesday, 742 players had at least 300 plate appearances in 2019 and at least 100 in 2020. Soto has the 11th-largest year-over-year wRC+ increase. Yes, Soto, who slashed .282/.401/.548 with a 142 wRC+ last year, is in the 99th percentile in yet another category: improvement. Soto has managed to bump his wRC+ by 52 points, and his line looks like something right out of a video game: .345/.480/.683, good for a 194 wRC+.

While Soto is putting up one of the best offensive seasons of the last decade — with the important caveat that this performance is easier to sustain over 60 games than 162 — there has not been, in my eyes, adequate buzz surrounding it. Perhaps with the focus on expanded playoffs and the extraordinarily close end-of-season award debates, we don’t have enough energy to focus on a player who will not be on a playoff team and will is not really in contention for any of baseball’s major awards. I’m here to change that; Soto has turned up his game another notch in a Trout-esque way, leaving us with questions that mostly start with, “How?”

First, look no further than plate discipline. Since his debut, Soto has always had great discipline. Among rookies who had at least 300 plate appearances in their first season, Soto had the fourth-highest walk rate, at 16.0%. He also only struck out in 20.0% of plate appearances, a touch better than the 2018 league-average. These numbers were consistent pretty much down to the dot in 2019: a 16.4% walk rate and a 20.0% strikeout rate. This year, however, those figures have basically flipped: Soto has walked in 20.1% of plate appearances and has struck out in just 14.5%. He leads baseball in walk rate and has the 18th-lowest strikeout rate. That is practically flawless discipline.

To do this, Soto has cut his year-over-year swing rate by four points and has the seventh-lowest swing rate overall. The majority of this decrease has come through fewer swings at in-zone pitches: Soto has dropped his Z-Swing% by more than six points, compared to an O-Swing% delta of just over two. Taking a closer look at the attack zones, Soto’s distribution of swings has changed markedly:

Soto’s distribution of swings by attack zone, 2019-20

Year Heart Swing% Z-Shadow Swing% O-Shadow Swing% Chase% Waste%
Year Heart Swing% Z-Shadow Swing% O-Shadow Swing% Chase% Waste%
2019 73.5% 59.0% 37.1% 14.0% 1.0%
2020 72.8% 53.8% 29.4% 9.4% 0.0%
Delta -0.7% -5.2% -7.7% -4.6% -1.0%

Given that Soto’s overall swing rate has been cut, it’s not a surprise to see that he has swung at fewer pitches in each attack zone. But what’s important here is that Soto has seen his greatest cut of swings on pitches that aren’t in his wheelhouse, represented best by the in-zone shadow column, and on pitches outside the zone overall, represented by the last three columns. But take a look at how these rates have changed when Soto is ahead or behind in the count:

Soto’s swings by attack zone, ahead vs. behind in count, 2019-20

Year Heart Ahead Z-Shadow Ahead O-Shadow Ahead Chase Ahead Heart Behind Z-Shadow Behind O-Shadow Behind Chase Behind
Year Heart Ahead Z-Shadow Ahead O-Shadow Ahead Chase Ahead Heart Behind Z-Shadow Behind O-Shadow Behind Chase Behind
2019 73.7% 60.6% 40.6% 10.9% 83.3% 73.0% 41.7% 19.5%
2020 65.6% 56.8% 30.4% 5.3% 94.7% 58.3% 38.7% 17.4%
YOY Delta -8.1% -3.8% -10.2% -5.6% 11.4% -14.7% -3.0% -2.1%
2020 League 75.2% 58.8% 40.9% 19.1% 86.4% 74.1% 55.5% 28.0%

There’s a lot going on in this chart, so let’s consider a couple of the highlights. First, in nearly every category, without respect to count, Soto deviates pretty significantly from the league-average. For example, look at Soto’s swing percentage on pitches in the heart of the zone while ahead in the count. Last year, he swung 74% of the time in those situations, which fell right in line with the league average. This year, he’s even pickier, only swinging 66% of the time. Similarly, compared to 2019, Soto is swinging less in almost every situation listed here with one major exception: pitches in the heart of the plate when behind in the count.

This is where we can truly understand the prowess of Juan Soto’s pitch recognition; while down in the count, he recognizes that he probably won’t get any better pitch than one in the heart of the zone, even if it’s not specifically to his liking. With all of this information considered, it’s not a surprise, then, that Soto ranks 11th in the majors in pitches seen per plate appearance. He also ranks 20th in called strike percentage. He truly waits for a pitch he can drive, and if he doesn’t get it, Soto is content taking a walk.

Pitchers are afraid to throw him strikes, too. Just 37% of the pitches Soto has seen this year are in the zone, seventh-fewest among qualified hitters. It’s not too drastic of a change year-over-year, though, as he did only see 38.5% of pitches in the zone last year. Thus, we can conclude that the big changes in Soto’s walk and strikeout rates truly are self-driven. One more stat that demonstrates this: Just 65.4% of Soto’s strikeouts are swinging strikeouts. That ranks in the 91st percentile. Last season, 72% of his strikeouts were swinging strikeouts. That was in the 79th percentile. That is, in essence, an outcome from this shift.

Soto’s improved discipline comes alongside better quality of contact. His expected batting average, expected slugging, expected wOBA and expected wOBA on contact are all way up, as is his hard-hit rate. He has crushed line drives and fly balls, posting an average exit velocity of 98.6 mph on balls in the air, ranking sixth-best in the majors. As a result, he has the highest barrel rate of his career.

But an important wrinkle in Soto’s 2020 performance is that his batted ball profile has some downside, which is a puzzling development to break down in the context of his excellent results. His average launch angle, for example, is down and his groundball rate, therefore, is up. In the fly ball era, it seems counterintuitive for a player to hit more balls on the ground and have more success. Simply, how has Soto had the third-largest decrease in year-over-year launch angle and is still the 11th-most improved hitter?

Sure, much of it is certainly the result of his discipline, but his batted ball numbers all look way better, too. If his 2020 performance was truly buoyed by BABIP and groundball luck, then his overall expected stats would surely be much lower than they are today. What gives?

Well, for one, this is why single point statistics sometime fail to tell the whole story. Soto is hitting more groundballs, yes, and that could be more of a problem if sustained long-term, but looking at his overall launch angle distribution shows why we shouldn’t really worry:

As you can see, the 2020 distribution closely mirrors 2019. The few extra groundballs are very apparent:

I would argue that this isn’t cause for concern, though. While Soto has indeed hit more groundballs this season, the launch angle drop is less of an issue when considering his median — as opposed to his average — launch angle. Soto’s median launch angle this season is 7 degrees, which is pretty much exactly where you want to be (when hitting the ball adequately hard enough):

Lots of hits, though admittedly not as good as 14 degrees, which was Soto’s median launch angle last year:

Ultimately, I wouldn’t be too concerned, though this could be something to watch in the future. But as long as Soto continues to demonstrate this ultra-elite discipline, all while hitting the ball very hard in the air, he can sustain a few more groundballs than normal. That’s captured in those expected statistics, all of which are very high — and better than they were last year — despite the increased groundball rate. He hits the ball much harder when he puts it in the air, and that, too, boosts his results.

Had Soto not missed the first handful of games due to what he thought was a false positive test for COVID-19, he probably would be in conversation for NL MVP right now. He’s having an incredible year, and though the baseball fandom side of our collective minds remains focused on the postseason, it’s important that we give a nod to Soto’s phenomenal year as well. Incredibly, he keeps getting better. And he’s still just 21 years old.

Devan Fink is a sophomore at Dartmouth College and a Contributor at Beyond The Box Score. Previous work of his can be found at FanGraphs and his own personal blog, Cover Those Bases. You can follow him on Twitter @DevanFink.