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Michael Wacha throws a wicked fastball

Is throwing a high fastball good? For Michael Wacha, it absolutely is

MLB: St. Louis Cardinals at Milwaukee Brewers Benny Sieu-USA TODAY Sports

Michael Wacha burst on to the scene in 2013 as a 21-year-old phenom. Drafted 11 months prior with the compensation pick the Cardinals received from the Angels for losing Albert Pujols, he ascended quickly to the MLB team. He made his debut on May 30th, throwing 7 strong innings, striking out 6, and allowing just 1 run to the Kansas City Royals. After beating the Pirates in a win-or-go-home game 4 during the NLDS, the highlight of his rookie campaign came in the next series where he outdueled Clayton Kershaw not once, but twice, on his way to winning the NLCS MVP.

Despite Wacha’s early success, it wasn’t until 2015 when he seemed to put everything together. Pitching to induce weak contact and throwing 180+ innings got him to 17 wins on the year and earned him an All-Star appearance.

The success in his rookie campaign (2013) can largely be attributed to his fourseam fastball. Throwing it 65% of the time and at nearly 94 mph, the pitch was worth 9.3 runs above average—a pretty impressive number considering he started the season at AA. Move to 2015 and his success was due to an improved curveball. The chase rate on the pitch rose 25% and produced a groundball rate above 60% (via Fangraphs). Interestingly, these aren’t elite numbers, but they were enough to put Wacha in an elite club.

It is my sincere belief (and hope) that Michael Wacha can return to his 2015 form and even improve by making a slight adjustment with his fastball.

To be clear, he has already begun that process. He is throwing the fourseamer at a career-high velocity (95.3) and the value of the pitch has drastically improved from an awful -6.2 runs above average (in 2016) to a respectable 3.2 runs above average with a couple months remaining this year (via Fangraphs). Much of this is due to an adjustment in his release point that is closer to where it was in 2015.


On the y-axis of this graph, negative numbers are toward third base, while 0 represents the middle of the rubber. In 2016, Wacha released his fourseam fastball closer to the middle of the rubber than ever before, and it didn't work out too well. The adjustment he made is a mechanical one, not a positioning one (as I wrote about here for Carlos Martinez).

Wacha is, undoubtedly, more of a pitch to contact pitcher than a strikeout pitcher. So, in general, it’s best that he keep most of his pitches low in the zone.


Wacha is just outside the top 20 of qualified pitchers with a groundball rate of 47.9%. He’s having success with this approach. When looking at only his fourseam fastball, the pitch breakdown is very similar.


Again, he is throwing most of his pitches low in the zone. While this is a good general approach, it would behoove Wacha to throw more high fastballs. What is the zone breakdown of batting average against his fourseam fastball?


In the bottom two rows of this chart, batters post an average of .312. However, in the upper two rows of the chart, batters post an average of .224. That would seem to indicate increasing the number of high fastballs is a good idea.

According to, Wacha’s fourseam fastball is averaging 10.37 inches of vertical movement, which is impressive despite it being a career low. But what does that actually mean? This pitch certainly doesn't shoot up in the air almost a foot. That would be absurd because, you know, gravity. Positive vertical movement means that the pitch drops, in this case, 10.37 fewer inches than a ball without spin.

Since Wacha throws his fourseamer with such a high spin rate, the pitch “rises” on hitters. In other words, it sneaks up on them, crossing the plate before hitters can get their hands around to swing. Take a look at the zone breakdown of Wacha’s fourseam fastball percentage whiffs.


Naturally, high fastballs are harder to hit. But with Wacha, that effect is exaggerated. Even his percentage whiffs per swing breakdown shows an uncanny ability to get whiffs up in the zone.


The downside to throwing high fastballs is that a mistake is more costly. A mistake on a low pitch might turn a groundout into a double. But a mistake on a high pitch is a home run. However, as Ben Markham (@Ben_Markham) mentioned in his piece on Paul Dejong’s extreme hitting profile, MLB hitters have “re-geared their swings towards hitting the low strike a long way.” So much so, in fact, that pitchers have slowly started to throw more higher fastballs (Jeff Sullivan of Fangraphs wrote a really interesting piece on the increase of high fastballs here).

Michael Wacha is the perfect man to pioneer this new trend. By throwing more fastballs up in the zone, he will become a more effective pitcher—both by decreasing his batting average against and by striking out more hitters. I’m not advocating for a change in his approach, with Wacha’s cutter and current fastball usage, he is more than capable of success. Still, he has the ability to use the high fastball as a weapon, which would certainly be to his advantage.

As always, credit to,,, and for the data used in this post.