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Mixing it Up: Tanner Bibee’s fastball, Matt Waldron’s knuckleball, and more

Time to 'float buy low offers' for Musgrove
Eric Samulski and Scott Pianowski analyze why it could be the right time to buy low on San Diego Padres pitcher Joe Musgrove after the veteran starter came off the IL.

Even though Spring Training is long behind us, we have no reason to stop looking into pitchers throwing new pitches. In fact, this is when the fun begins. Many pitchers will test new pitches in the spring but abandon them when the regular season starts. It can often be more informative to see which pitchers have drastically changed their pitch mix or pitch shape after a few starts in the regular season.

With that in mind, we will continue with the premise of the series I had called Pitchers with New Pitches (and Should We Care) by breaking down notable changes in a pitcher’s pitch mix (hence “Mixing” it up). We’ll look at pitchers throwing a new pitch, have eliminated a pitch, changed their pitch mix meaningfully, or are showcasing a different shape/velocity on a pitch.

I’ll continue my analysis with the simple premise that not every new pitch should be greeted with praise. A new pitch, like a shiny new toy, might be exciting on its own, but it also needs to complement what a pitcher already has and fill a meaningful void in his current pitch mix. We want to check and see if he has any splits issues. We want to see what his best pitch(es) is and see if this new pitch would complement that. Then we want to see what this new pitch type is generally used for (control, called strikes, etc.) and see if that is something this pitcher needs help with. We can also now see the pitch in action to look at the shape and command and see if it’s actually any good. Once we’ve done all that, we can decide if the pitch is a good addition or not.

If you missed any of the previous editions of this series, you can click this link here to be taken to the tracker, which I’ll update as the season goes on. It also includes links to the original articles so you can read them in full if you’d like.

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Tanner Bibee - Cleveland Guardians (Four-Seam fastball shape change)

Coming into the season, I had two main concerns about Bibee: his four-seam fastball wasn’t particularly good and he elevated his breaking balls too much. Guardians pitchers have long gotten away with that kind of mix, but Bibee got off to an inconsistent start to the 2024 season and was giving up more hard contact than last year. It might have been logical to assume his recent strong stretch has come on the back of improved breaking ball locations, but it could actually be a change to his four-seamer that’s fueling this.

Before we dive into the analysis, hat tip to Nick Pollack of Pitcher List for bringing this to my attention and also to Kyle Bland for creating an awesome four-seam fastball data app that PL Pro subscribers can use to track game-by-game characteristics of the pitch.

Let’s start with the season-long stuff data for Bibee’s four-seam fastball.

Tanner Bibee four-seam

Pitcher List

What we can see from this is that Bibee has slightly above average Induced Vertical Break (iVB) which tracks the amount that a four-seam fastball defies gravity and seems to “rise” as it approaches the plate. However, he has just a 0.5 Height Adjust Vertical Approach Angle (HAVAA) which factors in the height a pitcher releases the ball from and tracks the angle that the four-seamer approaches the hitter.

This is often a far more important metric because the importance of “rise” on a four-seamer is impacted by the height the pitch is released from. If it has good iVB numbers and is also released from a lower point, then it will be even more impactful up in the zone than a pitch that’s already released from a significant height. The higher the HAVAA number, the flatter the fastball, which means the less it drops and the greater the frequency of it staying up in the zone.

Well, over the last three starts, Bibee has seen an uptick in both his iVB and HAVAA. It started on May 13th against Texas, and in his last outing against the Angels, Bibee had an iVB of 16.5 inches and a HAVAA of 0.7. Those may not seem like huge changes from a numbers perspective, but they are definitely impactful and are made even more impactful since Bibee already does a good job of keeping his fastball up in the zone, where a flatter fastball can miss more bats and be more effective.

As you can see from this Pitcher List graphic, over his last three starts, Bibee’s location grades (plvLoc+) on his fastball have been great, and the 5.15 PLV grade is a significant improvement from his 4.96 season-long grade on the four-seam fastball, especially considering 4.95 is league-average for a starting pitcher.

Bibee fastball grade

Pitcher List

Over those last three starts, Bibee has allowed four earned runs on 13 hits across 18.1 innings, while striking out 18 and walking just four. He also has 18 whiffs on his four-seam fastball, granted 13 of those came against the Angels. Still, Bibee has taken his worst pitch and showcased a level on it that’s far superior. This version of his fastball is now an above-average offering to pair with his plus change-up and slider and a curveball that continues to show improvements.

VERDICT: POTENTIALLY IMPACTFUL. It’s only three starts, so we don’t want to overreact, especially since we’ve seen pitchers like Reid Detmers showcase new shape on their four-seam and then lose it shortly thereafter. However, if these changes continue, and Bibee appears to be deliberately trying to change his four-seam shape, then this could be a huge improvement for Bibee. I’d still want to see the locations on his breaking balls improve as well, but we can tackle one change at a time.

Matt Waldron - San Diego Padres (Knuckleball)

Matt Waldron is an interesting pitcher because he’s a knuckleballer who’s not really a knuckleballer. He’s upped the usage on the pitch by over 10% this year, and it is his main offering, but he also throws a four-seamer, sweeper, and sinker pretty consistently. The sweeper grades out as a pretty good pitch in its own right, but it doesn’t miss many bats, and since neither the four-seamer nor sinker do either, Waldron needs the knuckleball to dance for him if he’s going to have fantasy relevance.

So it’s noteworthy that his last three starts have featured a much different-looking knuckleball. For much of the season, Waldron’s knuckleball has sat between 76-77 mph. It was exactly 77 mph in a good start against the Dodgers on May 11th when he allowed just two runs in 5.1 innings while striking out six. In his next outing, on May 17th in Atlanta, he threw the knuckleball 78.2 mph and induced six whiffs on the pitch while holding the Braves to just one run in 5.2 innings and striking out 10. That’s interesting but just one start.

Then, on May 23rd he went into Cincinnati and threw his knuckleball 79.7 mph, getting eight whiffs and holding the Reds to two runs in five innings while striking out seven. He followed that up on Tuesday night with a 78.9 mph knuckleball against the Marlins that led to seven shutout innings with six hits and eight strikeouts.

Matt Waldron knuckleball vs MIA


He also threw his knuckleball 55% of the time against the Marlins, which is a massive development. He has never seemed to want to lean aggressively on the pitch during the season, always keeping it around that 35% usage. And it makes sense in many respects. Even though it’s his only true swing-and-miss pitch, it also allows a 47% Ideal Contact Rate (ICR), which is really high, and has just a 46% zone rate, which is low for a primary offering.

That’s part of the bargain with a knuckleball. It can be hard to command and easy to hit when it’s not dancing right. Having other pitches to rely on makes Waldron, in the Padres’ eyes, less volatile. However, it also makes sense that he would start to lean on the knuckleball more when he has this good a feel for it. And, truth be told, without the knuckleball, we’re not really interested in fantasy leagues.

But he now has 31 strikeouts in 23 innings against the Dodgers, Braves, Marlins, and Reds in his last four starts. That should pique your interest. We’ve seen knuckleball pitchers go on prolonged hot streaks, and we know that when that pitch is dancing, it can be impossible to hit. A harder knuckleball obviously gets on the hitter quicker, so they have less time to try and visualize where the ball will land and swing for that area which is how you attack a knuckleball since there is no clear movement pattern.

We have no idea how long this will last since it’s impossible to predict the consistency of a knuckleball. However, Waldron is making a deliberate change here, and it’s working so far, so we need to take note of it.

VERDICT: MINIMALLY IMPACTFUL. The added velocity is nice. I’m just saying “minimally impactful” here because, velocity or not, the knuckleball is a fickle pitch and it can abandon a pitcher at a moment’s notice. It’s nice to see Waldron being more successful with the pitch, and you can certainly use him while he’s on this heater, but even a change in the pitch velocity won’t give you any more security that it can be a pitch he commands well all season.

Michael Wacha - Kansas City Royals (Slider)

Michael Wacha tends to get overlooked in fantasy baseball (and probably by baseball fans in general) because he never quite lived up to the promise he showed when he broke through with the Cardinals years ago. However, he’s been a pretty good pitcher over the last three seasons. In 324.1 innings from 2022 on, Wacha has a 3.47 ERA and 1.16 WHIP. Yes, he doesn’t strike a ton of batters out, but he also doesn’t give up much loud contact so he can be a useful pitcher in deeper fantasy formats or as a streamer in shallow leagues.

Coming into 2024, Wacha didn’t seem to have any really splits issues, and he gave up the exact same 7.3% barrel rate to both righties and lefties last year. The biggest criticism may have been that he had a lower SwStr% (swinging strike rate) against righties, which is not ideal since he already had a poor SwStr% to begin with. Of course, Wacha’s best pitch is also his changeup, which will always perform better against opposite-handed hitters, so he could have benefited from a pitch he could rely on to miss bats against right-handed hitters.

It could be for that reason that he introduced a slider this season.

He debuted the pitch in his third start of the season, using it just 6.5% of the time against the White Sox. He barely used it over the next few starts but has started to lean on it far more of late.

Michael Wacha pitch mix


In his last outing against the Rays, the slider was tied for his most-used pitch, collecting five whiffs and registering a 34.6% CSW. It might not be a coincidence that he also posted his highest SwStr% of the season in that start while striking out seven batters in six innings.

He’s been using the pitch pretty much exclusively to right-handed hitters this year, throwing just three of his 72 sliders to lefties. The pitch has just 2.5 inches of horizontal movement and grades out as a below-average offering in both Stuff+ and PLV grades. Still, it does have an 18.1% SwStr% on the season and has allowed just a 16.7% Ideal Contact Rate (ICR). Wacha likes to use the pitch early in counts, throwing it 72.2% of the time early on, which is the 91st percentile in baseball. It also has a solid 71.4% first strike rate, so he has been successful at getting ahead with it.

The pitch doesn’t get many called strikes or swings-and-misses out of the zone, and that could be because Wacha struggles to command it right now. The pitch has just a 30.6% zone rate and 51% strike rate, both below average, and if you look at his strike zone plot, you can see how often he misses away.

Wacha slider

Pitcher List

However, we love to see that he is consistently keeping the pitch away from right-handed hitters, which is helping to prevent damage. New pitches can take a bit of time to learn how to command, so if we start to see even more improvement from Wacha in that regard, the pitch could become even more impactful.

VERDICT: MINIMALLY IMPACTFUL. As I mentioned above, the pitch isn’t there yet. He struggles to command it and he’s not using it much in two-strike counts, so it’s not going to lead to major changes in his strikeout rate. However, having another pitch to use to right-handed hitters that can keep them off his sinker and changeup will certainly help. His fantasy value will always hinge on his command and his changeup, but it’s never bad to add another solid pitch to your arsenal.

Cal Quantrill - Colorado Rockies (Splitter)

Cal Quantrill is on a nice run right now, and the people want to know why or if it can relied on. No. OK, thanks for reading.

OK, fine. Let’s dig in.

Quantrill has allowed just six total earned runs in his last five starts (23.2 innings) while striking out 32 batters. He had a terrible start against Houston at home before that but has allowed two or fewer earned runs in seven of his last eight starts. Now, only three of those seven starts came at home, but those were against the Phillies, Giants, and Mariners so he wasn’t getting full cakewalk matchups in Coors.

So how is he doing this? Well, a big component could be the splitter. It’s a pitch he added last year but threw just 12% of the time. He used it 32% of the time in April and is now up to 36% of the time in May. It’s easily been his best pitch this season and is a good offering to combat the altitude in Coors Field.

Quantrill Splitter

Pitcher List

So far in 2024, the splitter has just a 4.2% barrel rate allowed, a 1.47 Defense Independent ERA (dERA), and a 14.8% SwStr%. All of which are the best marks of any of his pitches. That SwStr% is below average for a splitter, but he’s potentially getting more comfortable with the pitch since he’s gotten nine whiffs on it in each of his last two starts. Stuff+ loves the pitch and Pitcher List’s PLV stat is less convinced but mostly because Quantrill misses middle with the pitch often, throwing it in the middle of the y-axis (so not high or low) 22% of the time, which is 74th percentile. He also throws the splitter up in the zone 17.7% of the time, which is the 81st percentile. Those aren’t the locations where you’re supposed to throw splitters.

However, even though the pitch is in the zone more often than other splitters around the league, he also has just a 19.5% ICR allowed on it, which is the 95th percentile in baseball. As a result, we actually don’t care if Quantrill throws the pitch in the zone because nobody is hitting it well.

The problem is that the rest of the arsenal isn’t great. His sinker is getting hit hard this year with a 48% ICR and his cutter has been even worse. His curveball does get a ton of called strikes, but he only uses it 9% of the time, so he’s really relying on the splitter for a lot of success this season. He worked on the pitch a lot in the offseason, and we often see pitches take a big leap forward in the second year a pitcher is using them, so it’s not a surprise that it’s been a good weapon for him this year. The issue is more that it’s his only real weapon and he still pitches on a bad team in a hitter-friendly park.

VERDICT: MARGINALLY IMPACTFUL. Look, the splitter is his best pitch. In that regard, it has made a clear difference for Quantrill. It makes him a pitcher you can consider when looking for streamers; however, I don’t think it makes him somebody who has “solved” Coors Field and so he will remain a risky and inconsistent fantasy option.