Welcome to Mixing It Up, a weekly column where I look at starting pitchers who are making noteworthy changes to their pitch mix or pitch shape/velocity. We often assume that the offseason is the only time that pitchers will make meaningful changes to their repertoire or their pitch shape. While it’s certainly a time when the most tweaking happens, there are many pitchers who continue to modify their pitch mix or their grip as the season progresses in the hopes of capitalizing on the results or pitch modeling they’re seeing.
In this column, I’ll break down three to five pitchers each week who have shown a change in their profile that has me intrigued. It won’t always be a pitcher who requires an immediate add but could be somebody who has worked his way onto our fantasy baseball radars or a pitcher I think is set to begin a productive stretch. I’ll always try to make sure we have enough of a sample size to work with and I’ll be mixing in both shallow and deep league targets, so there should be a little something for everyone.
Last week, I covered both Yu Darvish and Luis Medina who continued their strong run of performances this week, while I also shone a spotlight on Freddy Peralta who got hit hard by the Braves, and Cole Ragans, who got demoted before making another start. You can’t win ’em all.
With that said, let’s dig in to this week’s pitchers of note.
Chase Silseth – Los Angeles Angels
We’re going to lead off with Silseth because he might be the most intriguing name in this article. The 23-year-old was an 11th round draft pick in the 2021 draft out of the University of Tennessee. A little over a year after being drafted, Silseth made his MLB debut last season with the Angels and it did not go well, posting a 6.59 ERA across seven starts.
This season started off on a similarly inauspicious note with Silseth getting called up from Triple-A in late April so the Angels could use him as a multi-inning reliever. He threw five shutout innings before being lit up for seven runs in his next two appearances, and then the Angels debated turning him into a late-inning reliever.
Fortunately for all of us, and likely the Angels, the team allowed Silseth to keep starting in Triple-A, where he posted a 2.79 ERA, and then called him up last week for a spot start against the Yankees. The result was 10 strikeouts in 5.2 innings with just four hits and one earned run allowed. The right-hander had a 42% whiff rate and 45% CSW on the night in what was a pretty dominant start.
At the center of that tremendous performance was a re-worked slider.
When he was up earlier in the year, Silseth was throwing his slider 84.7 mph with 10 inches of horizontal run and -4.6 inches of drop. When Silseth came back up for the start against the Yankees, he was throwing a slider that was just 80.6 mph with 11 inches of horizontal movement and -10.6 inches of drop that almost acted like a sweeping curveball.
The pitch had a 25.6% swinging strike rate (SwStr%) in the start and looked truly dominant at times. What’s more, it seems like Silseth and the Angels knew that, which is why he threw the pitch 46% of the time after only throwing his previous slider about 15% of the time.
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The introduction of that slider, or curve or whatever he wants to call it, could be a massive game-changer for Silseth as it now gives him a true plus pitch to go along with his 95 mph fastball. However, the cutter that Silseth seemed to abandon in that start against the Yankees had been his second-best pitch on the year with a 14.7% SwStr% and 4.25 dERA, so the removal of it is questionable. His sinker has a solid 3.93 dERA but doesn’t miss many bats, and the splitter has been a pretty poor pitch for him so far this year, so I wonder if we’ll see the cutter come back.
Still just 23 years old, Silseth has time to continue to tweak his arsenal to build around the slider/sinker combination. I think bringing back in the cutter as a harder offering with less movement could be a solution, especially against lefties, but this is now a development that we should be watching closely.
Steven Matz – St. Louis Cardinals
Steven Matz has long been a darling in the fantasy baseball community, but the results just never seem to justify the frequent discussion of him as an underrated option. He struggled with consistency in New York, and then after a solid 2021 season in Toronto, he has battled injuries and poor performance since coming to St. Louis.
Yet, since June 1st, Matz has a 2.89 ERA, 3.48 SIERA, and 18.8% K-BB% in 28 innings. Granted, a large portion of that was as a reliever, but after re-joining the rotation in July, Matz has allowed five earned runs in his last 14.2 innings while striking out 19 batters and walking just four.
A reason for that success could be a subtle change to his pitch mix. After throwing his change-up just over 23% of the time to start the season, he has upped it to 33% in July while cutting down on his curve usage.
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That’s a noteworthy development because the change-up has been Matz’s best swing-and-miss pitch with a 15.8% SwStr% on the season. The change also has a -4.3-degree launch angle allowed, so it’s not a pitch hitters do a lot of damage on. It is a pitch that causes Matz to rely on his defense a lot, which has not worked in his favor this year with the Cardinals’ defense posting a -2 Outs Above Average (OAA) with Matz on the mound.
Aside from the change-up, another positive development for Matz has been that his sinker has averaged 95.1 mph in his three starts this month after averaging 93.6 mph at the start of the year. That has led to a 17% SwStr% and 0.02 dERA in July, as opposed to just an 11.1% SwStr% and 5.85 dERA in April.
Relying on his sinker/change-up primarily gives Matz two pitches that don’t allow a lot of hard contact and also miss a decent number of bats. However, his inconsistent curveball means that Matz is really just a two-pitch pitcher which keeps him a risky bet to have prolonged success. Still, while that velocity is up and changeup usage is heavily featured, Matz can remain a solid streamer.
Taijuan Walker – Philadelphia Phillies
Another inconsistent veteran finding some solid footing after a change in pitch mix is Taijuan Walker. The former Mets starter has made a few key changes since the summer hit, getting rid of his slider, reducing the usage of his four-seam fastball, and relying more on his cutter.
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Up until June 1st, Walker had a 5.57 ERA and 8.8% K-BB% over 11 starts, but from June 1st on, he’s posted a 2.67 ERA and 14.4% K-BB% over nine starts. That included a 1.50 ERA over 36 innings in June before beginning to slide back with a 5.00 ERA over 18 July innings.
So let’s see what has changed in July and if there’s any hope for Walker to get back to his June brilliance.
The first thing you notice is that Walker’s velocity on his sinker and four-seam is down about 1.5 mph in July. He’s at 107.1 innings this season, but he hit 157 innings in each of the last two seasons, so you wouldn’t expect him to be wearing down already.
Walker’s decision to dial back the usage of his four-seam was a good one since the pitch has a .282 batting average against on the season with a 6.57 dERA and 8.8% SwStr%. The cutter and sinker have been much better for him with a 3.41 dERA and 3.26 dERA respectively. However, neither pitch has a SwStr% over 6.7%, so he puts a lot of pressure on the defense if he relies on just those two pitches.
The sweeper did have a 10.5% SwStr% and a .207 xBA but it also allowed a 50% barrel rate in limited usage, so it likely was not the answer for Walker and removing it was a fine decision, especially since he relies on a splitter that has a 2.97 dERA and 14.2% SwStr% on the year to get his swings and misses.
So all of the pitch mix changes make sense for Walker, which is probably why June was such a strong month. However, he really only has one pitch that misses bats, which means he runs the risk that the contact he allows on the sinker and cutter will be damaging contact. We’ve seen that come into play in July as Walker has not allowed a single barrel in the month but has seen diminishing returns.
Going forward, I’m continuing to watch the velocity decline to see if it sticks, but it seems like Walker was simply over-performing in June and should settle into a low 4.00-ERA pitcher to finish the year.
Bryan Woo – Seattle Mariners
We’ll end with a high upside young arm that has made an intriguing change to his pitch mix.
In 44 MLB innings so far this year, Bryan Woo has an impressive 54 strikeouts and a 21.9% K-BB%; however, a recent run of poor starts has seen his ERA rise to 4.91 with a 3.80 xFIP and 3.54 SIERA. He has an impressive 14.5% SwStr% on the season, thanks to a fastball that has a 17% SwStr% and a slider with a 16.5% SwStr%.
However, Woo’s struggles against lefties (.403 average and .851 SLG) prompted the young right-hander to make a change to his arsenal in late June, bringing in a cutter and dialing back on his slider usage for a time.
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The cutter is 87 mph, and Woo still seems to be playing around with how much drop and cut to have on the pitch, adding more cut and less drop as he has continued to use the pitch. The tweaking has seemed to help the pitch, giving it a 103 Stuff+ as he has added more cut to it.
On July 3rd against the Giants and July 8th against the Astros, Woo’s cutter performed well, allowing just one hit and posting a whiff rate over 25%. However, he threw the cutter exclusively to lefties against the Giants and then pretty much exclusively to righties against a Houston team that lacks many left-handed bats, so the plan for the pitch was not fully clear.
In his next start, he used the cutter exclusively to lefties against the Twins, and he re-introduced the slider in a limited sample. The result was a truly poor performance, but that had more to do with his four-seam being hit hard and also giving up a home run on the sinker. Yet, the inconsistent approach with his complementary pitches remained.
Overall, Woo gets a lot of swings and misses on his four-seam, but he also gives up a lot of hard contact. The cutter still misses a decent number of bats but gives up far less hard contact, so finding a balance between those two offerings does make some sense; yet, it’s clear that Woo is still playing around with the proper mix of pitches. In my opinion, an arsenal that relied on the sinker and features a slider or cutter depending on the handedness of the hitter seems to make sense and could maximize Woo’s impact.
The young right-hander might only have another two or three starts before being shut down for innings concerns, so it’s unlikely he’ll settle on the best pitch mix in that time. However, he should remain a solid fantasy option against teams with few impact left-handed bats. That includes the Arizona Diamondbacks who he faces next, since Corbin Carroll is their only left-handed hitter who has the potential to do major damage. I would start Woo in that matchup and treat him as a risky, high-strikeout matchup-based play the rest of the way.