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Statcast Week 5: Yonder Alonso Continues to Mash

MLB: Detroit Tigers at Oakland Athletics
Behold! The Oakland A’s new home run overlord, Yonder Alonso.
Andrew Villa-USA TODAY Sports

I woke up yesterday morning to find that Fangraphs had posted an article about the very thing I was planning to write about today, so thanks for that Dave Cameron. Though, that isn’t surprising given the fact that Fangraphs writers write about interesting things across the league when they happen. Yonder Alonso, however, isn’t usually interesting. So why did Cameron write about him and why is he noteworthy? Today is May 9th, Alonso has already tied his career high in home runs with 9 long balls this season, and Alonso told us this was coming. That is interesting!

Back in March Eno Sarris took note of Alonso’s strong spring training numbers. Alonso told Eno, in simple terms, what he wanted to do.

“Did some mechanical things but also intent was important. I’m trying to punish it more, get it in the air.”

Eno also pointed out a change that Alonso has made, one that is commonplace in MLB: the increased leg kick.

Yonder Alonso, 2016
Yonder Alonso, 2017

You can see in those images that there is a noticeable difference in Alonso’s leg as the pitcher prepares to release the ball. The image on the left from 2016 was a warning track flyball. On the right is Alonso’s home run off of left-hander Daniel Norris from Sunday.

Alonso has done exactly what he set out to do, and something for which AN community member BootJosh has advocated since last year, and that is hit the ball hard and in the air. One of every two balls Alonso puts in play is a fly ball, increasing his flyball percentage from 33.3% in 2016 to 50% in 2017. His line drive rate is the same, as well as his infield flyball rate. However his groundball rate has significantly dropped as he’s figured out how to convert those batted balls into fly balls, or hard-hit fly balls rather.

Alonso hasn’t needed to hit the ball much harder to become more productive. For him it has simply been a matter of hitting the ball in the air with more frequency.

Yonder Alonso 2016 vs. 2017

Year Player Events BA ISO BABIP SLG wOBA xwOBA xBA Exit Velocity Launch Angle
Year Player Events BA ISO BABIP SLG wOBA xwOBA xBA Exit Velocity Launch Angle
2016 Yonder Alonso 412 0.253 0.114 0.284 0.367 0.299 0.331 0.27 88.2 10.3
2017 Yonder Alonso 70 0.298 0.34 0.311 0.638 0.424 0.413 0.288 90.1 21.1


Yonder Alonso’s Launch Angle, 2016
Yonder Alonso’s Exit Velocity, 2016
Yonder Alonso’s Spray Heatmap, 2016


Yonder Alonso’s Launch Angle, 2017
Yonder Alonso’s Exit Velocity, 2017
Yonder Alonso’s Spray Heatmap, 2017

As you can see Alonso has increased his average launch angle quite a bit. The increase in exit velocity will help too, which is where the leg kick and attempt to hit the ball harder comes in. It’s clear to me that Alonso is swinging with the goal of making harder contact and I’d say he’s succeeding, but at the sacrifice of his contact rate and strikeout rate. Nevertheless, Alonso’s contact and strikeout rates were so good to begin with that he can make concessions in those areas and remain above average, as he’s done.

Yonder Alonso’s Plate Discipline

YEAR Player BB% K% Contact%
YEAR Player BB% K% Contact%
2016 Yonder Alonso 8.5 13.9 83.9
2017 Yonder Alonso 10.5 22.9 78
2017 League Average 8.8 21.5 77.6

I’d like to point out that even though Alonso is striking out more than he ever has, he’s walking more than he ever has, too! I believe two things are at play here: First, Alonso is a more dangerous hitter and second, Alonso is swinging less overall, especially at pitches outside of the zone.

Alonso’s HR/FB rate is 25%, which is a huge increase from any year in his career. Is that number too large and likely to come down? Yes. The question becomes how much will it come down? Five qualified batters posted HR/FB% of 25% or better last year. Since 2010 only 20 batters have posted such a rate. Chris Davis of the Orioles is the only hitter to post a 25% HR/FB% and hit 45% flyballs. Since 2010 only two hitters have posted a 50% flyball% or better and a 20% HR/FB% or better: Chris Carter (2014) and Jose Bautista (2010). Nobody What Alonso is doing is unprecedented and doesn’t offer many clues as to whether or not it will continue.

I’m optimistic Alonso can settle between 18%-22% HR/FB% which puts him on a 30 HR trajectory and on pace for the best season of his career.

Other Athletics Statcast Notes

Oakland A’s Team Home Runs: May 2-May 8

Date Player Inning Distance Exit Velocity Launch Angle
Date Player Inning Distance Exit Velocity Launch Angle
5/2/17 Yonder Alonso Top 9 436 ft. 109.1 MPH 22.344 deg.
5/3/17 Yonder Alonso Top 4 393 ft. 107.1 MPH 25.25 deg.
5/4/17 Ryon Healy Top 7 413 ft. 104.4 MPH 25.771 deg.
5/6/17 Ryon Healy Bot 2 407 ft. 106.4 MPH 23.518 deg.
5/6/17 Yonder Alonso Bot 4 420 ft. 105 MPH 26.517 deg.
5/6/17 Yonder Alonso Bot 6 389 ft. 105.5 MPH 21.002 deg.
5/7/17 Yonder Alonso Bot 4 382 ft. 97.6 MPH 34.788 deg.
5/7/17 Ryon Healy Bot 9 367 ft. 104.3 MPH 41.375 deg.
5/8/17 Jed Lowrie Bot 4 387 ft. 100.6 MPH 23.802 deg.
5/8/17 Trevor Plouffe Bot 5 424 ft. 104.5 MPH 24.027 deg.
5/8/17 Jed Lowrie Bot 11 410 ft. 104.4 MPH 28.844 deg.