by 
Tyler Mahle was enjoying a successful 16th start of the season for the Reds last night until the 7th inning. Through the first six, Mahle had given up just one hit and two walks. He had struck out 8 batters.
Because of a short bullpen (Raisel Iglesias and Amir Garrett were unavailable), manager David Bell elected to let Mahle start the 7th inning. In the blink of an eye, the 24-year-old had given up a home run to Lorenzo Cain and a single to Eric Thames. Bell pulled Mahle after 102 pitches. It was the second game in a row the right-hander had crossed the 100-pitch threshold, throwing 103 pitches in Anaheim.
Mahle has always been known for his fastball command. It has allowed him to exceed the league average for starting pitchers in first-pitch strikes by a considerable amount. Mahle’s heater averages 93 mph and tops out around 96 mph.
The question with Tyler Mahle’s development as a major league pitcher has been whether he could improve secondary pitches to go with the fastball.
So far in 2019, there is encouraging evidence that both his off-speed pitch and breaking ball (particularly the former) are becoming increasingly effective and they were on devastating display last night.
The various information services that classify pitches have different interpretations of Mahle’s arsenal and how it has changed from last year. Mahle throws a breaking ball about 20-25% of the time. He’s changed it from a slider to a curveball. Mahle throws an off-speed pitch about 12-13% of the time, or one out of every eight pitches. Whether it’s classified as a change-up or splitter, it comes in around 87 mph.
Last night, Mahle threw 55 fastballs out of 102 pitches. That usage rate is a bit lower than his average for this year (59%) and far below last year’s usage rate of 68%. The Brewers put only four of Mahle’s 55 heaters into play last night.
But let’s look at Mahle’s all-important secondary pitches.
Let’s start with pitch outcomes. Mahle has doubled his whiff percentage on off-speed pitches from 9 to 18% in 2019.
Mahle has raised his ground ball rate (GB%) from 34 to 56.5% with his off-speed pitch and from 40 to 50% with his breaking ball.
In terms of batted ball outcomes, Mahle’s breaking ball (slider/curve) wOBA has fallen from .378 to .298. His wOBA against on off-speed pitches (change-up/splitter), has dropped from .414 to .258. Mahle’s off-speed pitch has seen a decline in isolated power against (ISO) from .264 to .147.
Likewise, batting average against has declined from .340 to .235 on Mahle’s off-speed and breaking ball.
Last night, Mahle moved from the fastball, to curveball, to off-speed pitch as the game progressed and he worked through the Brewers lineup multiple times. His first strikeout was on a fastball, but his next two were on curves. Four of his next five were on his splitter, including K’ing Christian Yelich. His seventh strikeout was on a curve.
So there are early promising signs that Tyler Mahle is taking a big step in his development as a pitcher. He’s becoming more effective with both a breaking ball and an off-speed pitch to pair with his already outstanding fastball.
[Featured image: https://twitter.com/Reds/status/1137134044695547904]
