As baseball fans, it’s easy to sometimes think about major league players as finished products, even when they first make their debut. In and of itself, being called to the big leagues feels like validation that a player is pretty much done with the part of his baseball life that includes all the learning, the growing, the changing, the adapting. A ball player’s foundation is built in little league, high school and, if they choose, college, and the rest is fine-tuned in the minors. Surely, players get better over the course of their major league careers, and continue to develop. But the various tools, traits and weapons that accompany them on that journey are already present at the beginning. When you’re watching a rookie play in the majors for the first time, you’re witnessing someone who’s learned how to utilize his skills in the best way possible get the opportunity to put those skills to the test, and prove once and for all whether all those years of work were enough.
Of course, we know all of that isn’t true. Who, regardless of profession, is a finished product at 23 years old? Major leaguers of all ages and experience levels learn new tricks all the time, because constant adaptation and growth is what the game demands. But even then, some players arrive for the first time looking the part of someone who has less to learn than most. When Tyler Mahle made his first major league start in September 2017 at age 22, he did so with a reputation for being one of the most polished pitching prospects in baseball. He had good enough fastball velocity to beat hitters, and complemented it with three secondary pitches that he could command as well as anyone in the minors. Even at a young age, Mahle looked like a complete pitcher.
His first extended stint in the majors in 2018, however, revealed he had much longer way to go than anticipated. He finished with a 4.98 ERA and 5.25 FIP in 112 innings, and after never walking more than 3.3 batters per nine innings at any level of the minors, he walked nearly 4.3 per nine in the big leagues, and gave up 22 home runs. Mahle still hit his spots as well as nearly anyone in the majors, as The Athletic’s Eno Sarris wrote about last May. But as the season wore on, his numbers only got worse. After holding a 3.86 ERA in 44.1 innings before that Sarris piece ran, with opponents hitting .246/.311/.455 against him, he allowed a 5.72 ERA in 67.2 innings the rest of the way, with opponents crushing him to the tune of a .305/.390/.505 line. His finally five appearances of the year were even more gruesome — a 14.49 ERA in 13.2 innings, and a .420/.506/.725 batting line against him.
Simply put, the things Mahle did to pile up outs in the minors weren’t working against major league hitters. His fastball was mostly fine, essentially holding up as an average pitch over the course of the season — not incredibly encouraging for someone who relies on his fastball for more than 67 percent of his pitches, but not a lost cause, either. His secondary pitches, however, were basically unusable.
|wCH in 2018||Value|
|wCH in 2018||Value|
Mahle generated the third worst total value in all of baseball with both his change-up and his slider in 2018. Landing on just one of these lists probably means you didn’t have a great season. The fact that Mahle landed on two was damning. The positive takeaway from all of this, if there is one, is that Mahle knew these pitches were trouble. Talking about his slider with The Athletic’s C. Trent Rosecrans, Mahle is quoted in the Sarris article linked above saying, “my slider is terrible. I’ve just never figured out my slider, really. I’ve been able to locate my changeup, not my slider. I’m not exaggerating, it’s been my worst pitch so far.”
This winter, as the Reds added three new starting pitchers to the roster and gave Mahle a more difficult road back to the rotation than he had at the end of 2018, the now 24-year-old decided to rework his pitching arsenal entirely. He ditched the slider in favor of a curveball — a pitch he’d thrown just 20 times in the majors through last season — and reshaped his change-up into more of a split-fingered fastball.
The results of the change, at least so far, have been positive. For starters, his surface numbers have taken a significant step forward — in 39 innings, his ERA is down to 3.69, his FIP is down to 3.32, and his xFIP rests at a very cozy 3.08, ranking ninth best among major leaguers with at least 30 innings. He’s raised his strikeout rate from last year by seven percent, while cutting his walk rate by 57 percent. Overall, he’s on a 4.1 fWAR pace over a 32-start season.
On a pitch-by-pitch basis, it’s easy to see improvements between the slider and the curve, and the old changeup and the new one.
Neither of his new offerings are dominant, but they are demonstrably better than what he had last year. The batting averages are down, obviously, but the overall quality of contact is especially key here. Each of his new off-speed pitches have also been more difficult to elevate — last year, his slider and changeup resulted in launch angles of 13 and 15 degrees, on average. This year, his curveball has generated an average launch angle of 7 degrees, and his splitter has a launch angle of just 3 degrees. All of that contributes to one of the more important developments of this season for Mahle — a ground ball rate that sits at 45.4 percent, way up from 38.7 percent a year ago.
But while the results Mahle has gotten from his new secondary pitches have been encouraging, they aren’t even the entire point. In a conversation with The Cincinnati Enquirer’s Bobby Nightengale back in February, Mahle said the larger goal of his new pitches is to make his fastball more effective.
“I think it’s going to be a lot more consistent, I think, just because of the way I throw my fastball,” Mahle told The Enquirer. “I try to throw everything else off that. The curveball and the split are a lot easier to throw off that.”
He’s had just 39 innings this year to put that theory to the test, but so far, it seems Mahle was right. According to FanGraphs, his fastball has generated the 15th highest value in all of baseball this season. That rates him as having the best fastball on the team, an impressive feat for someone who pitches on the same staff as Luis Castillo, who averages 3.1 miles per hour more on his heater than Mahle does.
In his start against Oakland on Tuesday — in which he went six innings and allowed just one run on three hits and a walk while striking out eight — Mahle showed his best fastball of the season, with FanGraphs rating his wFB at 2.4 for just that game. Here’s what that fastball looked like against A’s left-handed hitters, who went 1-for-7 with four strikeouts against Mahle’s heater.
It’s pretty difficult to spot a four-seamer better than that. Lefties have been a headache for Mahle ever since he made the major leagues, sporting a thoroughly unpleasant .300/.414/.576 line against him in 2018, and a .415 wOBA. His line against lefties in 2019 still isn’t great, but it’s much more playable: .305/.339/.508, with a .359 wOBA.
A large part of that improvement comes from better command over his fastball. When Mahle’s heater is on, he can get it to spin from a left-handed hitter’s hip all the way back to the inside corner. Here’s a strikeout Mahle got against Mets outfielder Brandon Nimmo that illustrates what that looks like:
As you could imagine, Mahle’s ability to locate a fastball while maintaining that kind of movement on it can make a big difference. Here are his fastball heat maps against left-handed hitters in 2018 versus 2019.
Last year, Mahle allowed his fastball to sail back over the middle of the plate, where it would run directly into the barrel of opposing hitters. This year, he’s staying right on the corner with it, and when it does break back into the center, it’s staying above the hitter’s hands. He’s still in the strike zone as much as he always was — his zone percentage has gone up four-tenths of a percentage point this year from last — he’s just staying on the edges more.
Mahle’s fastball location has more to do with simple execution than his pitch mix, though, and the latter is what this article is about. That brings us to the following two heatmaps, comparing where his primary off-speed offerings were located in 2018 vs. 2019.
Because he doesn’t generate a high spin rate on his breaking pitches, Mahle’s success depends greatly upon where he spots them. Too often, his slider and changeup would hang at the thigh, begging to be slugged over everyone’s heads. His curve and splitter, though, stay at the knees or sink well below them. If you’re looking for evidence of Mahle’s newfound ability to get ground balls, this ought to go a long way toward explaining it.
It isn’t uncommon to see a major leaguer add a third or fourth pitch, take a pitch away, or slightly tweak one. It’s less common, though, to see a pitcher do what Mahle has done. He took two pitches he threw a total of 31 percent of the time in 2018, replaced them with two new pitches that he’d virtually never experimented with in the majors before, and thrown those with 33 percent of his offerings. He hasn’t mastered anything yet, struggling with each of his three main pitches at various points. But in Tuesday’s start against the A’s, for the first time all season, his fastball, curveball and splitter all graded out as average or better. Mahle still isn’t a complete pitcher, just like he wasn’t when he first debuted. He seems closer now, though, than he’s ever been. He’s still learning, growing and changing, trying to be a little better each day than he was the day before. Aren’t we all?