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Highlighting Pitching Breakouts Due to Arsenal Changes

I examine the changes that have led to Packy Naughton, Johan Oviedo, and Junior Fernandez breaking out this year.

MLB: Los Angeles Dodgers at St. Louis Cardinals Jeff Curry-USA TODAY Sports

One of my favorite things to do every season is to look at pitchers, and especially breakout pitchers, and see if they have changed anything about their arsenals. So, with the team coming out of the break, that’s what I set out to do.

There are quite a few breakout pitchers this year, and, unsurprisingly, I found plenty of changes. From arsenal adjustments to velocity gains to new pitch shapes, we’ll cover all the things that a few of the breakout arms have changed.

In this article, I’ll focus on Packy Naughton (everybody’s favorite arm), Junior Fernandez, and Johan Oviedo.

Hopefully this gives you something about each of these players to pay attention to for the rest of the season.

Packy Naughton (3.68 ERA, 3.02 FIP, 22 IP)

Packy Naughton might be everyone’s favorite pitcher this year. Between the high-wire acts, the name, the dependability when T.J. McFarland stumbled out of the gate, and the hair, he’s become an immediate fan favorite. He only reinforced that position with his Houdini act against the Dodgers a few weeks ago.

The fun thing about Packy is that he pretty much came out of nowhere. He never really pitched well in college as he posted ERAs near 7 in each of his final two seasons at Virginia Tech, though he did have some early professional success as he was the Reds Minor League Pitcher of the Year in 2019.

His production cratered after being sent to the Angels, but you can hardly blame him for that. It is the Angels after all and they really can’t develop pitching.

So, to make a long story short, a guy who was DFA’d and then picked up off waivers has become a fan favorite and bullpen hero. How did this happen? Well, Naughton basically changed everything.

We’ll start with his slider because that’s the most notable change.

Packy Naughton’s New Slider

Year Vertical Movment (in) Horizontal Movement (in) Spin Direction wOBA xwOBA Whiff Rate (%) Pitches
Year Vertical Movment (in) Horizontal Movement (in) Spin Direction wOBA xwOBA Whiff Rate (%) Pitches
2021 35.4 3.7 12:45 0.478 0.409 28.0 50
2022 44.0 3.6 4:00 0.383 0.248 43.5 68

The first thing that should jump out at you is the massive jump in vertical movement. The pitch added an extra 9 inches of drop. That’s huge! And unsurprisingly that has coincided with an increase in his ground ball from 50% to 66.7%. I included the sample size in the table so we wouldn’t get ahead of ourselves here. There’s a chance that the groundball rate comes back down as he throws more slider, but in theory, the increase makes sense.

I also don’t want you to see the .383 wOBA against the pitch this year and think that his reshaping of the pitch didn’t really change it’s effectiveness. It will be an effective pitch. All of the expected numbers are lower and Naughton is getting a ton of whiffs against the offering. It’s harder to hit and I expect that to show in the second half.

You can tell he trusts it more because he’s throwing it more. It’s up to almost 20% usage after being mired around 13% last season. Again, I know we aren’t dealing with a ton of pitches here, but that’s significant.

The new slider shape also brings tunneling into the picture. The pitch now, on average, is much closer to having opposite spin when compared to his fastballs. On a pitch-to-pitch basis, though, he is able to match the spin of some sliders with the spin of some fastballs, and when he doesn’t, he doesn’t miss by much.

On average, his slider is 7:00 away from his sinker and 6:45 away from his four-seamer, but when you look at the image below you can see that he does achieve opposite spin (which looks the same to a hitter) between his slider and some of his other pitches.

That’s much better spin deception that he had last year with his slider.

Naughton seems to be a fastball/changeup guy but his new slider has given him a go-to breaking ball that he has the confidence to throw.

Naughton has done more than just revamp his slider, though. He’s added more velocity. It’s no wonder his four-seamer has gotten better when the extra 2 mph are added to an extra 2 inches of rise. That’s a great recipe for more effectiveness, and especially more effectiveness at the top of the zone.

The curious thing is that Naughton’s slider has actually gotten 3 mph slower. That’s probably helping him get more total movement too.

Normally I would like to see a harder, sharper slider, but the slower profile seems to be working well with the new shape to get whiffs, so I’m fine with it for now. Let’s see what happens to the pitch the rest of the year and let the results speak for themselves.

Junior Fernandez (0.68 ERA, 3.11 FIP, 13.1 IP)

This has already been covered a bit but this season Junior Fernandez has begun throwing his sinker almost exclusively, dropping his four-seam percentage from 43.3% last year to just 6.5% this season. His sinker rate has gone the other way, rising from 4% usage to nearly 45%.

Perhaps unsurprisingly the change has made Fernandez a groundball fiend. He’s getting groundballs at a 65% rate now after sitting below 50% in previous years.

Hitters have pretty much been unable to do anything against Fernandez’s sinker as the pitch has surrendered just a .274 wOBA. The difference in Fernandez isn’t solely due to his arsenal tweak, though. I mean, he’s never really had an effective fastball. It’s always had elite velocity, but it’s always been crushed, regardless of whether it was a four-seamer or a sinker.

The real change for Fernandez has been his command of the pitch His zone rate on his sinker is currently 57.3% and he’s never had a zone rate that high on either fastball. The next best was 55.9% on his four-seamer in 2020 but that hardly counts since he only threw 34 pitches.

That’s really been the key for Fernandez all along. He’s always been a flamethrower but that doesn’t matter too much without an ability to throw strikes.

Now, I don’t want to get ahead of myself because there are still plenty of red flags. First off, Fernandez has struggled to throw non-fastballs in the zone with both his slider and changeup being thrown outside the zone more than 23 of the time. That’s likely the reason why he has a below average chase rate despite such nasty stuff. No one is going to swing at a pitch that’s hardly ever in the zone.

He also has a walk rate of 10.7%, which is definitely more than a touch high. It might be fine for Fernandez, though. Let’s compare him to fellow flamethrower Jordan Hicks. Hicks posted walk rates of 13.3% in 2018 and 10.0% in 2019 and he was still able to pitch effectively those years.

To be fair, Hicks did get more strikeouts, but I’m expecting Fernandez’s strikeouts to tick upwards soon, especially if he can start throwing his secondaries for strikes.

The sinker has been Fernandez’s best friend. His improved command and velocity of the pitch has made it a dominant offering and it’s made him a viable reliever after a few years of poor results.

Johan Oviedo

I think it’s fair to say that Johan Oviedo belongs in the bullpen full time. He never really pitched well as a starter in the upper levels of the minors or in the majors but he’s really taken hold of a bullpen role this season.

That’s because it’s allowed him to drop his changeup entirely and focus on his four-seam fastball/slider combination.

This is beneficial in two ways because Oviedo is now throwing his two favorite pitches almost 90% of the time and he’s no longer throwing his worst pitch. It’s no wonder he’s broken out this season.

Last year, Oviedo’s changeup was bad. Really bad. He allowed an incredible .638 wOBA against the pitch. Quite honestly, you could make a case that it was his changeup which prevented him from being a good pitcher in 2021 as his fastball, slider, and curveball all allowed a wOBA under .325.

The 24-year-old threw 117 changeup last season and surrendered three home runs with the pitch. Of the 21 plate appearances that ended with a changeup, 11 ended with the runner reaching base. It simply was an awful pitch. Not that he’s not throwing it, he’s doing much better.

The fastball/slider focus has been beneficial for Oviedo because those are the two pitches he’s always been most capable of throwing for strikes. Command has always been his biggest problem but the focus on those two pitches has helped him drop his walk rate from 12.8% to 6.7%.

He’s actually landing his fastball in the zone more than he ever has and his slider is being thrown for a strike well over half the time. So, it’s no wonder that his chase rate has shot up 5% from last season. Now that he can actually land his pitches in the zone consistently, he’s tempting hitters to swing more often.

What’s really interesting is that Oviedo’s four-seamer and slider have actually been worse this year than they were last year.

Johan Oviedo’s FB/SL Combo

Year Pitch wOBA Usage
Year Pitch wOBA Usage
2021 Four-Seam Fastball 0.324 53.3%
2022 Four-Seam Fastball 0.399 43.3%
2021 Slider 0.309 23.7%
2022 Slider 0.321 42.8%

One thing that has helped Oviedo this year is dropping his fastball usage well below 50%. Even though his slider is putting up worse results relative to last year, it’s still been much more effective that his four-seamer this season.

But the thing that has really helped him, as I said above, is dropping his changeup. I mean, look at the table above. In 2021, his fastball had a wOBA of .324. His slider had a wOBA of .309. His curveball had a wOBA of .257. That accounted for 89% of his arsenal. wOBA is scaled the same way as OBP, so if you know was a good OBP is, then you know what a good wOBA is. Thus, none of those wOBA’s are really that great, yet Oviedo ended the year with a 4.91 ERA.

It’s because 11% of his pitches got hammered. Sure Oviedo has refined his command this season, but simply removing the changeup from his arsenal has made him so much better.

His improvement isn’t quite done, though. He could still stand to throw fewer meatballs and hit the edge more often. Throwing strikes is only the first part of the equation. Now he needs to harness his pitches enough to put them on the black consistently.

Also, as an aside, I would love to see Oviedo experiment with a sinker. His fastball doesn;t get a ton of whiffs, it’s never been super effective, and it drops a lot more than the average sinker. Even last year, when his four-seamer was decent, he still had a .354 expected wOBA with the offering to go with an 89.1 mph average exit velocity and 13.6% whiff rate. That’s really not impressive. And those numbers are slightly worse this year.

Oviedo doesn’t get the rising effect that makes fastballs swing-and-miss pitches at the top of the zone. If the pitch is already going to drop, then I would love to see him switch to a sinker and add some run too. That may even help him get more groundballs.

It’s not an easy change to make, especially when Oviedo has never really shown a sinker at the major league level. His four-seamer simply doesn’t profile any better than an average pitch and I would love to see what he could do with a sinker that tails a lot more.


Each of the pitchers that we’ve looked at have some changes behind their breakouts seasons and it’s these changes that make me hopeful the breakouts are here to stay. They haven’t simply lucked into a breakout season. Rather, they have tweaked things to try and find what works.

So, as the season continues, watch for these things we’ve covered:

Packy has a better slider and a fastball that can play well at the top of the zone.

Fernandez’s sinker-reliance makes him a dangerous pitcher but watch and see if he can keep throwing the pitch in the zone.

Notice how Oviedo’s fastball/slider combination has made his low-usage curveball even more effective and how his newfound strike throwing ability has made him a viable arm.

I love seeing pitchers make changes to make things work and that’s what these three have done. They have become three of my favorite arms to watch this year and they’ve gone a long way towards making the St. Louis Cardinals bullpen such a weapon.