It’s hard to believe that Mike Foltynewicz is still only 26 years old. It seems like he’s been providing about equal parts brilliance and frustration for Braves fans for years, but 2018 is only his 3rd complete season in an Atlanta uniform, after making his debut in a half-season cameo back in 2015.

We’ve seen outings like last year’s near no-hitter in Oakland, in which Foltynewicz lasted 8 full innings, striking out 8, and showing glimpses of why he’s always been regarded as one of the premier arm talents in all of baseball. There have been more outings like these, such as back in 2016, when Folty struck out 11 White Sox and didn’t walk any of them. We’ve also seen a lot of clunkers, meltdowns, and balls flying out of the park. If we’re being honest, we’ve probably seen more of that than of the previous type of outing.

This has been the essence of Foltynewicz throughout his Major League career—peaks, valleys, and a lingering thought of “What if?”. What if he could harness his raw talent and become more of a refined pitcher? What if we could expect strings of dominant outings from the affable, red-bearded hurler instead of momentary glimpses?

The changeup, they say, is the missing link for so many young starting pitchers (especially of the hard-throwing variety) that are trying to turn a corner. Many of them never find it, and most of those that never find it never turn that corner. Clichéd and trite as it may sound, Mike Foltynewicz knows this as well as anyone.

For your viewing pleasure (?), here is a chart of what left-handed batters have done to Folty to this point in his career.

wOBA vs. .365 ISO vs. .215 K% 19.8% BB% 9.3% FIP 4.94

That’s not great! While Foltynewicz’s career numbers against same-side batters are much better (.324 wOBA, 22% K-rate, 3.93 FIP), his Achilles’ heel to this stage in his career has been lefties, which have absolutely given him nightmares. A starting pitcher, in order to be successful long-term, has to have some semblance of an ability to limit opposite-sided hitters. Opposing managers have stacked their lineups against Folty with left-handed hitters, and with good reason. Lefties have a track record of hitting Foltynewicz and hitting him long and hard. 34 of his 62 career home runs surrendered have come against them, and a general inability to put lefties away has prevented him from ever becoming the pitcher that his pure talent says that he could be.

Let’s now take a look at what the 2018 version of Mike Foltynewicz has done versus lefties.

wOBA vs. .305 ISO vs. .172 K% 28.0% BB% 14.0% FIP 3.76

Yes, I know. It’s early in the season, and this will likely change. Even though I believe that Foltynewicz has made real adjustments that have allowed him to more effectively neutralize left-handed hitters, it is likely that some type of regression will knock him back towards his career norms when it comes to these numbers.

But still, wow. Strikeouts are up, contact is down, and lefties haven’t been able to tee up as many gopherballs against Foltynewicz as they have throughout the rest of his career. Walks are elevated, but you can live with this. This is a stark, significant statistical change that isn’t reflected in his numbers against right-handed hitters.

Foltynewicz career vs. RHH

wOBA vs. .325 ISO vs. .163 K% 21.8% BB% 6.7% FIP 3.93

Foltynewicz 2018 vs. RHH

wOBA vs. .298 ISO vs. .116 K% 23.9% BB% 6.8% FIP 3.64

There seems to have been some marginal improvement against righties for Folty in 2018, mainly in terms of sprinkling in a few more punchouts, but these numbers are much more in line with his career numbers than his numbers against left-handers.

So, this begs the question—why? I now present two GIFs of two changeups. One is a changeup thrown by Mike Foltynewicz this season. The other is a changeup that he threw last season. Guess which is which.

You might’ve noticed that Changeup 2 comes from a Braves home game against the Marlins, which is something that hasn’t happened yet in 2018. If so, way to go, genius! So yeah, Changeup 1 is from 2018 and Changeup 2 is from 2017.

These GIFs are reflective of the mechanical changes that Foltynewicz has made in order to better harness his change-of-pace weapon and make it a more effective weapon against hitters, especially of the left-handed variety. Foltynewicz is throwing his changeup at an average of about 89 mph this season, which is up about 3 mph from what he averaged last season. He’s throwing a harder, more authoritative changeup with slightly less vertical drop than his old changeup, but with a smoother and more deceptive delivery and approach than in the past. He’s sacrificed a bit of movement for a lot more deception, and that’s worked for him so far.

Another major difference is that he’s simply using the changeup more often this season. His changeup usage rate has doubled in 2018 compared to in 2017, with him throwing the changeup around 11% of the time this season, including a rate that pushes 17% against left-handed batters. Whereas his changeup in the past was often a “show-me” pitch in which he didn’t have much confidence, it’s taken a step forward and is now a quarter of a legitimate four-pitch arsenal possessed by the righty.

Let’s take a look at some of Foltynewicz’s pitch tendencies in 2018:

Pitch Type Usage% vs. RHH Usage% vs. LHH Avg. Velocity Whiff% 4SFB 39% 45% 96.1 8.6% Sinker 14% 16% 96.6 3.9% Slider 41% 11% 85.1 16.9% Curveball 3% 12% 79.1 7.7% Changeup 3% 17% 88.5 14.9%

As you can see here, while Folty has continued to use a mostly two-pitch mix against right-handed hitters, anchored by an often-excellent slider, he has become a true four-pitch pitcher against lefties. Whereas Foltynewicz used to rely more on his curveball and slider against opposite-sided hitters, the increased confidence in and usage of his changeup has allowed him to more effectively keep lefties off-balanced and uncomfortable at the plate. He has excellent whiff rates on both his slider and changeup this season, and has also to induce plenty of swings and misses with his hard four-seam fastball.

Folty is largely the same pitcher that he’s always been against right-handed hitters, but the mechanical refinement of his changeup and his surge of confidence in the pitch has allowed him to take a step forward thus far in 2018. Foltynewicz seems to have discovered a cure to his ails against lefties, and thus, appears to be progressing towards the image that many have had of him as a potential quality mid-rotation MLB starter. This development would serve as a massive boon for the Braves, a team that looks to be pretty set offensively but is still looking to improve on the rubber, especially when it comes to its starters.

The right-handed flamethrower still has his warts. He sometimes falls into a rhythm of telegraphing his pitches by utilizing a varied arm action when using his fastball versus his breaking pitches, as @PitchingNinja visualized after Foltynewicz was roughed up by the Giants in his 5-inning, 9-hit, 6-run, 4-strikeout outing against them back on May 4th.

Folty–Tipping Pitches (arm swing stutter/96mph Fastball vs smooth arm swing/84mph Slider). pic.twitter.com/4gY1rlYKsa — Rob Friedman (@PitchingNinja) May 5, 2018

Foltynewicz is also prone to frustration due to umpires’ interpretations of the strike zone at times, and he tends to occasionally lose focus and let his mechanics get away from him when things start to take a turn from the worse. It is certainly true, however, that he has improved greatly in this regard since his Braves debut and that he should continue to make strides in this area as he gains more experience and maturity as a pitcher.

I wrote this analysis on the eve of Foltynewicz’s May 10th, 2018 start against the Marlins in Miami. All statistics in this part of the analysis are current as of before the start. Now, I’m going to take you through tonight’s start by Folty through my eyes, illustrating some of the tendencies that I pointed out in my above analysis and taking a look at how these changes were implemented and manifested 9 (or not) in game action.

Foltynewicz had a solid start against the Marlins, although it was somewhat inefficient. He lasted only 5 innings after being lifted for pinch-hitter Preston Tucker in a two-out, two-on situation, but he probably could’ve lasted another inning or two. He struck out 4 hitters (all of which were right-handed hitters) and walked 2. The only run that he allowed was unearned, as Lewis Brinson came around to score on a Martín Prado single after reaching base on a Johan Camargo throwing error.

He actually only generated 4 whiffs in the entire outing, 3 of which were on high 4-seam fastballs, and the other on a quality low-and-away slider to start off Starlin Castro’s at-bat in the 3rd inning. Folty threw 86 pitches (54 of them for strikes) with the following breakdown:

4SFB 39 (45.3%) Sinker 14 (16.3%) Slider 26 (30.2%) Curveball 4 (4.7%) Changeup 3 (3.5%)

As you can see, Foltynewicz used his changeup as little as he has all season in this start. This likely has something to do with the fact that the Marlins, to the contrary of nearly every other team that has faced Folty so far this season, had 7 right-handed hitters in their lineup versus only 2 lefties last day. As I mentioned before, Foltynewicz is a fastball-slider pitcher against right-handers, and unsurprisingly, over 90% of his pitches last night were fastballs or sliders. He largely worked a high fastball/low-and-away slider combination to hitters in order to keep them off balance and uncomfortable, and he located his fastball quite well. He mostly did a good job with the command of his slider, burying plenty in zones low and away that induced weak contact, but also made a couple of mistakes that, fortunately, were not turned into hits by the weakest lineup in baseball.

It is worth noting that Foltynewicz did continue to struggle with inconsistent arm swing motion in this outing. Many times, when throwing his fastball, he featured the brief pause or stutter that was highlighted by Rob Friedman earlier in the article. While it didn’t appear every time that he threw a fastball, such as on this 98 mph heater that he blew by JT Realmuto in the third inning…

It did pop up at other times, such as here, when he dialed up to 99 mph on a first-pitch strike to Justin Bour in the first inning.

This will be something to monitor for Folty as he goes forward, and something that he should clean up, as some hitters and teams may be able to take advantage of this occasional pitch tipping.

While this start wasn’t good for my analysis of Foltynewicz’s changeup and new tendencies against left-handed pitching, as he had only four opportunities to face them all game and only threw three changeups in total, it did illustrate his tendency as a pitcher to work up and in with fastballs and low and away with sliders to righties. He didn’t need more than an occasional change-of-pace yesterday, and that was okay. He got the job done either way.

In conclusion, it seems to me that if Foltynewicz is able to continue to throw the harder version of his changeup and maintain confidence and reliance upon the pitch against left-handed hitters, he’ll be able to turn a corner and neutralize more left-handed hitters than he has been able to neutralize to this point in his career. At-bats against southpaws have been what has limited Foltynewicz as a mediocre starting pitcher to this point in his career, but if he continues to utilize his improved changeup against them, his ceiling as a quality mid-rotation starter, or maybe a bit more, is well within reach.