It’s All in Z-Swing: Outliers in MLB

Khris Davis

Khris Davis had a Z-swing% of 82.2% in 2019. He had a Z-contact% of “only” 77.8%. It was a down year in general for baseball’s Mr. Consistency. His batting average of .220 varied from his typical .247 for the first time since 2014.  The real hint in the difference in Davis’ Z-contact% could actually lie in his slugging percentage. That number cratered to .387, the lowest it’s been since Davis’ first foray into AA ball in 2011.

Davis marginally increased his percentage of batted balls pulled in 2019, to 40.4%, so this doesn’t look like a case of Father Time reducing his bat speed.  Neither his strikeout numbers nor his walk rate were much different than his career norms. From these numbers, this looks like Davis was pulling off of pitches, either swinging over or ahead of pitches that wound up in the zone, perhaps as pitchers used a greater variety of offspeed pitches to curb his prodigious power.

Luke Voit

Luke Voit had a 2019 Z-swing% of 78.6% in 2019, with a Z-contact% of 78.1%.  Voit’s major league experience prior to this year was limited to 62 games with the Cardinals in 2017, so comparisons and conclusions about his performance are tricky, at best.  His OBP of .378 was solid, indicating a good knowledge of the strike zone overall. His high pulled pitched rate of 47.9% could again be a contributing factor, while his strikeout rate of 27.8% indicates a likely hole in his swing path that pitchers were able to exploit.  It remains to be seen if he closes that hole going forward.

Franmil Reyes

Franmil Reyes’ Z-swing% in 2019 was 77.6%, while his Z-contact% was 76.8%.  As with Voit, 2019 was Reyes’ first full season of MLB at-bats, making it harder to draw meaningful conclusions.  Reyes wasn’t a pull-hitter, with 43.1% of his hits toward center field. His .310 OBP was not stellar by contemporary standards, with a 28.5% strikeout rate appearing to be a strong contributor there.  Here, again, it looks like a batter with a good idea of the strike zone, but a weakness in a certain part of that zone, or against a specific type of pitches, or both. His performance going forward will help clarify that weakness, and his ability to address it.

Bryce Harper

Bryce Harper had a Z-swing percentage of 77.3% in 2019, with a Z-contact% of 79.3%.  Harper’s been in the league for eight seasons now; you might have heard of him.  Whether he’s in the running for an MVP, or having a season that pundits call “disappointing” measured against Harper’s real or imagined potential, his underlying stats for 2019 were largely in line with his career norms.  Harper is known for his plate discipline, but he’s also well-known for his unusual batting stance with its lots of fiddly bits. The idea that tiny changes in his approach in-season can lead to brief cold stretches at the plate has been much discussed, and is the most likely culprit behind his ever-so-slightly lower than expected Z-contact%.

Ryan McMahon

Ryan McMahon’s Z-swing percentage was 76.7%, while his Z-contact% was 78.3%.  Like Reyes and Voit, this was McMahon’s first full season in MLB. He had major league experience in two prior seasons, so conclusions about his performance are a bit more well-grounded in his history.  McMahon sported a .330 OBP despite a 29.7% strikeout rate in 2019. Those numbers, as with Voit and Reyes, point to difficulty with certain pitches, either in their location or their movement.