2023 has been the year of rookie starting pitchers. We’ve seen a veritable tidal wave of top prospects take a big league mound for the first time in the early stages of the season, and many have lived up to the hype. Taj Bradley, Eury Pérez, Bobby Miller, Tanner Bibee, and Andrew Abbott are just a few of the rookies currently impacting their respective teams’ starting rotations.
Among these arms, one stands out to me as perhaps the most interesting due to his extremely skewed pitch arsenal and general approach to pitching. Mariners righty Bryce Miller has been one of my favorite arms to watch throughout the 2023 season because his game plan is about as simple as it gets: blow the doors off of hitters with the fastball and worry about secondaries later.
That’s not an exaggeration, either. Roughly 70% of the pitches Miller has thrown in 2023 have been four-seam fastballs, with another 5% allocated to cutters. He is completely relentless with the heater and shows no fear throwing it in the zone to the best hitters the sport has to offer.
This approach was working wonders for Miller over his first few major league outings. The first five starts of his career yielded a total of 31.1 innings and just 4 earned runs allowed with 28 strikeouts and 3 walks, good for a 1.15 ERA, 1.86 FIP, 22.7 K-BB%, and .144 wOBA against. He was throwing fastballs almost 90% of the time during this stretch, and hitters were clearly overwhelmed by his vicious aggression with the pitch.
Since the end of May, however, Miller has run into some trouble. His 6th and 7th big league starts were completely disastrous, as he yielded a total of 15 earned runs over 7 innings to the Yankees and Rangers. Whereas opponents were lucky to make contact against Miller throughout most of May, contact became frequent and hard extremely quickly as the calendar flipped to June.
Miller’s most recent outing against the Marlins was a nice return to form, but that two-start stretch reminded us that he is indeed a rookie and is not impervious to the struggles that come along with facing major league hitting for the first time.
So the question now is what went wrong in those two outings, why was he so dominant initially, and what does he need to change in order to maintain some level of consistency?
In order to answer these questions, we’ll need to dig into Miller’s arsenal, how he’s deploying it, and what obstacles and limitations he’s currently facing that may prevent him from reaching his astronomical ceiling. Let’s start our discussion with what is by far the best aspect of Miller’s game.
Fastballs
Put simply, Bryce Miller’s four-seam fastball is electric. Among rookie starters to make it to the major leagues this year, only the aforementioned Taj Bradley has a four-seamer that is able to rival Miller’s in terms of sheer ride and in-zone dominance.
He has thrown the four-seamer 69% of the time in 2023 and 73% of the time in 2-strike counts, making it not only his main primary offering but also his main putaway pitch. That should be a good indicator of his level of confidence with the heater, and that confidence is backed up by the pitch specs.
Miller’s four-seam fastball averages 95 MPH with 19 inches of ride and just 3.5 inches of arm-side run, making it one of the straightest and hardest four-seamers thrown by any pitcher in the entire league.
This is something we’ve known about Miller for a good while. His FanGraphs scouting page had his fastball at a 70/70 grade upon graduation, while his next best attribute was his slider at a 50/55. The overpowering nature of his fastball has translated to the big leagues and has served as the foundation of his arsenal, which isn’t surprising.
The question for Miller is how often can he get away with throwing the four-seamer when he needs to work through opposing lineups for the second and third times in a given start. He’s struggled with getting through lineups a third time, posting a .357 wOBA against compared to .236 the first time through and .252 the second time through. His arsenal, as it currently stands, doesn’t look deep enough to dispel hitters from adjusting to the fastball after seeing it once or twice.
The other fastball featured in Miller’s arsenal is the cutter, which he only throws about 5% of the time. It’s not particularly special as far as cutters go, with just 2 inches of carry and 2.8 inches of arm-side cut at around 86 MPH. The ideal cutter should have around 8 inches of carry and around the 0 horizontal movement line with a slightly lower velocity than the four-seamer.
I suspect Miller’s “cutter” may be a poorly classified slider, but he definitely has a distinct cutter-like pitch he has used thus far. Whether it is a cutter or a hard gyro slider with some slightly manipulated shape is up for debate. Regardless, the results for this mystery pitch have been exceedingly poor, so he’ll likely either ditch it or totally repurpose it sometime down the line.
Changeup
Miller is throwing his changeup 5% of the time this year, and that’s pretty much all I can tell you about it. He’s only thrown about 40 of them so far, and they come in hard at 85 MPH with 9 inches of carry and about 16 inches of arm-side run.
Unlike the cutter, this is definitely its own pitch and I actually think there’s potential here. Miller kills vertical break really well on it and he gets about as much arm-side run as you could want from a changeup. Throwing it as hard as he does is kind of a mixed bag, as there are guys who have a good amount of success with hard changeups that have relatively similar movement profiles to their fastballs.
It’s not a pitch Miller likes to go to in high-leverage situations or to put hitters away, as he only throws it 3% of the time in 2-strike counts. His execution of it has also been extremely inconsistent, but 40 pitches is too small of a sample to draw definitive conclusions on. I like the movement profile and think he should try throwing it more to lefties.
Breaking Balls
Bryce Miller, last time I checked, pitches for the Seattle Mariners and was developed in their organization. This likely means he throws at least a couple of different breaking ball shapes, likely a sweeper and/or a gyro slider.
Well, would you look at that!
Indeed, Miller’s primary breaking ball is a hard gyro slider (14% usage), but he also throws the (very) occasional sweeper. The gyro slider comes in at 85 MPH with 0.3 inches of ride and 4.3 inches of arm-side break, while the sweeper averages 82 MPH with 3.7 inches of drop and 17 inches of sweep.
The gyro slider is extremely tight and serves as his main secondary compliment to the fastball, as he’s also thrown it 14% of the time in 2-strike counts. It has yielded questionable results thus far, with just a 5.6% swinging-strike rate despite a .157 wOBA against. Not really the type of discrepancy that inspires much confidence, especially for what should be your best breaking ball. His main slider grades out well with a 114 Stuff+, so there is some hope on that front.
The sweeper is a mystery at this point given that he’s only thrown about 50 of them. Still, it’s concerning that he’s barely recorded a single whiff with it, but I’ll just chalk that up to small sample madness for now.
The last breaking ball that Miller has in his repertoire is the curveball, and it’s a pretty mediocre offering all things considered. Again, he hasn’t thrown many of them so it’s tough to evaluate the pitch with any certainty, but it has registered a 100 Stuff+ with 7 inches of drop and 12 inches of run. Nothing terrible, but likely more of a show-me pitch in the long run.
Now that we’ve gone through Miller’s arsenal thoroughly, we can look into the adjustments he needs to make in order to capitalize on his monstrous potential.
Too Many Heaters?
We’ve established that Bryce Miller’s four-seamer is a fantastic pitch. There’s absolutely no denying it. It has fantastic characteristics, grades out well in stuff models, and has yielded strong results on the field (13% swinging-strike rate, .268 wOBA).
Still, can Miller really continue to throw the fastball around 70% of the time and maintain success deep into outings?
If Miller were to continue throwing fastballs at this current rate, it would be among the highest fastball usage seasons by a starting pitcher in the statcast era:
Miller would also be on pace to crush the statcast era record for highest fastball usage in 2-strike counts with 73.4%, the next highest being Nelson’s 68.3%. What this indicates to me is that Miller quite simply does not have a secondary pitch he feels he can consistently execute when he needs to put hitters away. That is a problem.
On that list of highest fastball usage by a starter in the statcast era, the only truly great season in the top 20 was Strider’s 2022. Strider made it work because he had an incredible fastball and an even more incredible slider to pair with it. He had a truly elite two-pitch mix, and even then he added a changeup for the 2023 season. He had two of the best pitches in the sport and still decided that wasn’t enough!
Watching Miller’s two blowup outings against the Yankees and Rangers, it was clear that his failure to execute secondary pitches in fastball counts was a huge issue. Major league hitters are smart. If they know you can only consistently execute one pitch, it doesn’t matter how good that pitch is, they’ll hit it eventually. It may take two or three times through the order, but they’ll hit it.
The incredible thing about a guy like Bryce Miller is that, despite his issues with his existing secondary arsenal, he still has a chance to be great with high fastball usage.
Generally speaking, it’s much better to have your best pitch be your fastball as opposed to a breaking ball or changeup. Having a great fastball gives you the ability to fall back on a pitch you can consistently command and draw whiffs with, and it’s easier to develop a good breaking ball over time than it is to develop a great fastball.
Miller is just one of those guys with the God-given ability to generate a ton of backspin on the fastball and just throw it over hitter’s bats. That is a fantastic skill to have and it gives him an opportunity to make the most of his arsenal. It’s not like he’s incapable of spinning the ball or throwing a good changeup. The pitch characteristics are there.
What Miller needs to do to truly cement himself as a force in the Mariners’ starting rotation is get to the point where he’s confident in his raw stuff outside of the fastball. He has three average or above-average pitches according to Stuff+, not just one.
Figuring out a better shape for that cutter (or adding one, if it is just a tighter gyro slider), likely by adding some ride to it and tightening up its arm-side run, would do wonders for his arsenal immediately.
It really looks like his slider is just aimlessly changing shapes between a sweeper and a tight gyro slider without a clean separation between the two, which could be affecting his execution and feel for the pitch over the course of an outing. I’d like to see him really start to throw a true cutter and clean up the shapes of his sweeper and bullet slider as he gets deeper into his young career.
Regardless, Miller is one of the most talented and exciting arms we’ve had the pleasure of watching during this 2023 season. We don’t get many guys who just come out shoving one pitch down opposing lineups’ throats at all, especially not starting pitchers. It’s been fun watching him dominate some weaker lineups with his elite four-seamer, but look for him to start figuring out what to do with his secondaries to take that next step as a big-league starter.
Photo courtesy of Icon Sportswire | Adapted by Aaron Polcare (@bearydoesgfx on Twitter)