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The Sultans of Swing (Rates)

Which Cardinal swing rates have changed the most?

MLB: St. Louis Cardinals at Cincinnati Reds Orlando Ramirez-USA TODAY Sports

It’s still very early in the season, a preamble I feel obligated to write in every article in April and May. The Cardinals have played 24 games, or a little more than 14% of the season. If the 2019 season was The Godfather (1972), we might not have even seen Jack Woltz spooning with Khartoum yet. That doesn’t mean some stats can’t be used to make inferences. Some stats stabilize faster, and swing rate is one of the quickest. It takes just 50 plate appearances before you can start to rely on swing rates. With that in mind, let’s take a look at some early returns compared to 2018.

First, Cardinals non-pitchers are swinging 0.4% more than they did in 2018. That might not seem like a lot, but the rate league-wide has fallen 0.9%. The Cardinals are swinging more while the rest of the league is swinging less. Their 0.4% increase in swing rate is the fifth highest increase in the league over 2018.

Here’s how individual Cardinal swing rates have changed since 2018, and their percentile amongst all hitters in the league. For my sample, I’ve included all hitters with 250 plate appearances in 2018 and 30 this year for a total of 244 players.

Cardinal Swing Rates, 2018 vs. 2019

Name 2019 Swing% 2018 Swing% Swing Diff Swing Diff Pctile
Name 2019 Swing% 2018 Swing% Swing Diff Swing Diff Pctile
Marcell Ozuna 44.70% 48.50% 3.80% 77.16%
Harrison Bader 42.70% 45.10% 2.40% 66.67%
Dexter Fowler 41.50% 42.00% 0.50% 49.18%
Paul DeJong 47.10% 45.80% -1.30% 34.98%
Paul Goldschmidt 44.30% 42.30% -2.00% 27.98%
Jose Martinez 45.60% 43.60% -2.00% 27.98%
Kolten Wong 44.30% 41.60% -2.70% 20.99%
Yadier Molina 57.00% 52.60% -4.40% 9.47%
Matt Carpenter 41.80% 37.10% -4.70% 8.03%

Note that the higher the percentile rank, the less the hitter is swinging overall. Marcell Ozuna and Harrison Bader are upper third in decreasing their swing rates since last year. On the other hand, Matt Carpenter, Yadier Molina, Kolten Wong, Jose Martinez, and Paul Goldschmidt are bottom third, with Paul DeJong just missing the cut at 34.98th percentile. They’re swinging more than last year, considerably so in some cases. Carpenter and Yadi, the two most tenured Cardinals, have the highest swing rates of their careers. Yadi is 2.7% higher than his previous career high and Carpenter is 2.6% higher than anything he’s done since his rookie year. Goldschmidt is 2% higher than anything he’s done since 2012. Ozuna’s change is just as significant in the other direction, 2% lower than any other swing rate he’s ever posted.

Of course, not all swings are the same. It’s generally a good idea to swing at more pitches in the zone and swing at fewer pitches outside the zone. In-depth knowledge like that is why I’m an analyst, folks. “Swing at good pitches, don’t swing at bad ones. Salt it salty.” I digress.

Fangraphs gives us both of those tools with O-swing% (percent of swings on pitches outside the strike zone) and Z-swing% (percent of swings on pitches inside the strike zone). Those take longer to become reliable than raw swing rates, but they can still help add some context to the increased swing rates in the table above. The Cardinals have collectively increased their Z-swing% by 2%, the third biggest increase in baseball. They’ve also decreased their O-swing% by 1.3%, though the entire league has decreased the same amount. Here’s how individual Cardinals have changed since 2018:

O-Swing and Z-Swing Changes, 2018 vs. 2019

Name O-Swing Diff Z-Swing Diff O-Swing Pctile Z-Swing Pctile
Name O-Swing Diff Z-Swing Diff O-Swing Pctile Z-Swing Pctile
Wong 2.00% 3.60% 73.66% 76.34%
Molina 2.00% 9.70% 73.66% 96.71%
Carpenter 0.90% 9.30% 64.82% 95.68%
Martinez -0.50% -0.90% 55.35% 42.59%
Ozuna -1.00% -9.20% 50.21% 4.53%
Goldschmidt -1.50% 5.10% 45.06% 85.60%
DeJong -2.40% 4.40% 37.65% 82.31%
Fowler -4.30% 4.10% 25.51% 80.25%
Bader -6.30% -0.10% 13.37% 49.59%

For clarification, the lower the O-Swing percentile, the less the hitter is swinging at pitches outside the zone compared to 2018. A high Z-Swing percentile means the hitter has changed significantly compared to 2018 by swinging at more pitches inside the zone.

In this case, Bader and Dexter Fowler have some encouraging numbers. The size of their O-Swing reduction is upper quartile in the league. DeJong is a little more moderate but has also decreased his O-Swing percentage a little better than the rest of the league. No hitter ranks in the bottom quartile in terms of swinging more outside of the zone, but Wong and Yadi just barely miss the cut.

When it comes to identifying pitches in the zone and swinging at them, six regulars- Yadi, Carpenter, Goldschmidt, DeJong, Fowler, and Wong- are in the upper quartile of biggest changes since last season. That’s exactly how the Cardinals have the fifth biggest swing rate increase this year. While it’s not great that they’re swinging more in a vacuum, they’re at least swinging at the right pitches.

Marcell Ozuna is ever the outlier, slashing his Z-Swing rate by a whopping 9.2%. Only 11 other hitters in baseball have cut their Z-Swing rate more. Considering his increased production, the assumption is that he’s being more selective on pitches in the strike zone leading to more damage. That certainly holds true when we look at ISO (.190 last year in the zone vs. .513 this year) and xwOBA (.398 last year, .491 this year). He’s also hitting more pitches in-zone at optimal exit velocity (95 mph or higher) and launch angles (22-38°). Last year, 9.7% of his in-zone balls in play were optimal. This year, it’s all the way up to 20.6% in the admittedly small sample. In short, nobody should care that Marcell Ozuna is swinging at fewer pitches in the strike zone if this is the result.

Overall, it’s an improved profile from 2018. It’s also leading to better results, with walk percentages up 1.3% from last year and strikeout rates slightly down from last year (0.2%). Since the end of that terrifying first week when they were striking out 29.4% of the time, they have the fifth lowest K% in the game (19.6%). Not all of it is sustainable, but at least the enhanced plate approach gives them a better shot at holding on to more of the increased production.