by 
Tyler Mahle passed several pitchers in the Reds organization who had been higher ranked prospects because of his fastball command. Two years ago, at the age of 23, Mahle earned more than 20 major league starts. He followed that up last year, with 25 starts and 129.2 innings despite missing August with a hamstring pull.
What has been the key to Mahle’s early success? Fastball command.
First-pitch-strikes are one way to measure a pitcher’s control. In 2019, 104 major league starters threw at least 120 innings. Of that group, Tyler Mahle had the 5th best “first-pitch-strike” rate, following guys named Paddack, Scherzer, Bumgarner and Tanaka.
The remaining uncertainty about Mahle’s development as a major league starter doesn’t concern his heater. It’s about secondary pitches. Last year, in his ongoing search to find the right primary partner for his fastball, Mahle all but abandoned his slider in favor of a curveball.
The big news from his start Tuesday night against the Cubs was his move back to that slider, at least for one night.
The obvious caveat with analysis this early in the season is that one game isn’t near enough of a sample size to tell us anything. So we won’t draw conclusions about Mahle’s path forward based on his first start, especially since he may not get another for a while. But we can look at his use of the slider and see what worked and what didn’t.
Mahle in 2019
Before we start in on Tyler Mahle’s 2020, let’s do a quick review of his 2019 season. First, Mahle’s pitch portfolio:
- 57% Fastball (93 mph)
- 23% Curveball (80 mph)
- 13% Split-Finger (87 mph)
- 7% Cutter (90 mph)
Here’s a chart that shows how Mahle performed in 2019 compared with his own 2018 season and with the 2019 MLB average for starting pitchers.
Based on these metrics, it’s reasonable to reach two conclusions: (1) Mahle improved across the board in measurements that pitchers control, and (2) he was better than major league average.
Some might point to Mahle’s 5.14 ERA in 2019. But as we know, ERA is a lousy way to measure how a pitcher actually pitched. xFIP, SIERA and xwOBA are examples of much better stats that are easily accessible. xwOBA looks at the quality of contact the pitchers gave up plus his strikeout and walk rates. Mahle was better than league average in xwOBA in 2019.
[Much of what goes into an ERA — like team defense, park size, scorer decisions, opponent lineup sequence, dumb luck — is out of the pitcher’s control. One example of that is the fate of runners left on base when a pitcher leaves a game. The average of so-called bequeathed runners that score is 30%, which was the case for Reds starters in 2019, with one glaring exception. Of the 14 runners Tyler Mahle left on base, Reds relievers allowed 11 to score. If Mahle had received average bullpen support, he’d have given up seven fewer Earned Runs and that adjustment to his ERA alone would have lowered it to 4.65.]
But even though Mahle was better than league average last year, he wasn’t much better. Tyler Mahle had plenty of room to improve. A big part of the reason for that was the ineffectiveness of his curveball, particularly against left-handed batters. Mahle’s xwOBA for his curve against LHB was an ugly .393.
Has Tyler Mahle decided to return to his slider as a way to fix that?
Mahle’s first 2020 start
On Tuesday night, Tyler Mahle threw 69 pitches over 4 innings against the Cubs. He faced their lineup exactly twice. Here is his pitch portfolio:
- 55% Fastball (94 mph)
- 29% Slider (85 mph)
- 12% Changeup (89 mph)
- 4% Curveball (80%)
At least for one night, Mahle substituted his slider for his curveball as his main secondary pitch.
Sometimes it’s hard to differentiate a pitcher’s breaking balls. That’s not the case with Tyler Mahle. His curveball comes in at 79-80 mph while his slider is consistently thrown at 83-86 mph.
Before we get to Mahle’s slider, let’s look at the other three pitches he threw. Cubs manager David Ross stacked his lineup with left-handed hitters. Six batters in the order were lefties. Mahle didn’t throw many curveballs or changeups, but those he did went strictly to left-handed hitters. He handled right-handed batters with his fastball and slider.
Mahle threw 38 fastballs — his best pitch. They ranged from 93-96 mph. The three times he hit the top end of that range were in the first inning. Here’s a 96.3 mph fastball from Mahle that Javier Baez watched go by for a called third strike.
Mahle threw his slider 20 times Tuesday night. He integrated it from the start and continued using it through his four innings. Let’s analyze examples that were effective and those that weren’t.
Exhibit 1 The first slider Mahle threw was to Cubs leadoff hitter Anthony Rizzo on a 2-2 count. Mahle got it inside on the left-handed hitter. It starts in the strike tunnel at first then breaks off the plate. Rizzo weakly grounds to the opposite field. This slider was effective.
Mahle does the same thing to Rizzo in his next at bat. Slider low and inside. It looks like a Mahle fastball coming as a strike, but breaks off. Rizzo whiffs. If Mahle could consistently use his slider like this against left-handed hitters it would be a huge step in his development.
Exhibit 2 Mahle’s second slider was to a right-handed batter, Javier Baez. He throws it on the 0-0 count for a first-pitch strike and Baez, who is probably looking for a fastball, lets it go.
Two notable things about this pitch. First, having the control to throw the slider for a first-pitch strike makes Mahle’s fastball more effective. Second, this pitch is spotted well. It’s not just a strike, it’s on the outside and lower part of the strike zone. No way Baez wants to swing at that on a 0-0 count. Effective.
Exhibit 3 Here’s a slider thrown to a right-handed batter the next inning again on a 0-0 count. But this time, Mahle is well off the plate. Batters, like Baez in the previous example, are looking for fastballs on the first pitch and let breaking balls go. Throwing one that isn’t a strike at 0-0 is ineffective.
Exhibit 4 Here’s another slider to the same batter as Exhibit 3 but later in the count. Because it’s 2-2, David Bote has to guard against a strike call, so he swings at this pitch off the plate. Effective.
Exhibit 5 Not all of Mahle’s sliders thrown for strikes were in good spots. This example is from the second inning after Jason Kipnis hit the soft fly ball that Shogo Akiyama lost in the sun. Mahle gets behind Nico Hoerner, works his way back to a full count, then throws this slider over the heart of the plate. No chance. Ineffective.
Here’s another slider example that falls in the same category, this time to a left-handed batter. Mahle has Kyle Schwarber (Middletown) 0-2 then throws this cookie in the middle of the strike zone. You can see from Mahle’s reaction he was disappointed with the pitch location. Ineffective, but worked out.
Exhibit 6 We’ll conclude on a good example. This is Mahle’s last slider of the game. In fact, it’s his final pitch. With two runners on in the fourth, this slider gets him out of trouble. Mahle throws it for a strike on an 0-0 count with that element of surprise. Hoerner check-swings into a double play. Effective.
Conclusion
Despite steady progress and performing better than MLB average, Tyler Mahle lost his spot in the 2020 Reds rotation when the club signed free agent Wade Miley to a 2-year, $15 million contract. Miley gives the Reds a left-hander in the rotation and he has a successful, although short, history with pitching coach Derek Johnson.
I’ve been skeptical of the Miley signing from the start and a charter member of Team Mahle > Miley. But for now, Miley is in and Mahle is out as long as the Reds five starters are healthy.
To be sure, Tyler Mahle remains a work in progress. He’s 25 years old and still figuring out what to throw beyond his plus fastball. Last year, Mahle switched to a curveball and it wasn’t the answer at least to left-handed hitters. Tuesday night, Mahle went back to his slider as his main secondary pitch.
The recipe for Mahle’s slider’s success is clear. Throw it for a strike on 0-0 counts as a change of pace. Throw it off the plate as an out pitch, inside to lefties and outside on right-handed batters. Avoid throwing it in the middle of the plate, something Mahle did too often Tuesday night. But taken as a group, producing a stellar .151 xwOBA, the 20 sliders have to be judged a success.
That said, don’t read too much into Mahle’s four innings. It’s foolish to draw conclusions from data this limited. Mahle might revert to his curveball in his next appearance. But that choice — and its execution — is at the heart of Tyler Mahle’s progression as a major league pitcher.
