MLB Starting Pitcher News: Chase Burns' debut, Kumar Rocker cuts it up

NBC Sports

5 hours ago

It's Wednesday, which means it's time for us to visit the bump on Hump Day and discuss starting pitcher news. Each week in this article, I'll be taking a deeper look at a few trending/surging starting pitchers to see what, if anything, is changing and whether or not we should be investing in this hot stretch.
The article will be similar to the series I ran for a few years called Mixing It Up (previously Pitchers With New Pitches and Should We Care?), where I broke down new pitches to see if there were truly meaningful additions that changed a pitcher's outlook. Only now, I won't just look at new pitches, I can also cover velocity bumps, new usage patterns, or new roles. However, the premise will remain the same: trying to determine if the recent results are connected to any meaningful changes that make them worth investing in or if they're just mirages.
Each week, I'll try to cover change for at least four starters and give my clear take on whether I would add them, trade for them, or invest fully in their success. Hopefully you'll find it useful, so let's get started.
Most of the charts you see below are courtesy of Kyle Bland over at Pitcher List. He created a great spring training app (which he's now carried over into the regular season) that tracks changes in velocity, usage, and pitch movement. It also features a great strike zone plot, which allows you to see how the entire arsenal plays together. I'll also use Alex Chamberlain's awesome work with his Pitch Leaderboard.
Matthew Pouliot,
Since returning to the Rangers' rotation in June, Rocker has a 4.61 ERA, 1.54 WHIP, and 15/6 K/BB in 13.2 innings. However, much of that is tainted by a poor first start against the Rays. He allowed just two runs on nine hits in 10.1 innings against the White Sox and Pirates in his last two starts, and while that is beating up on some poor opponents, Rocker also came back to the big leagues armed with a new pitch and a revised approach.
Pitcher List
As you can see from this Pitcher List chart above, Rocker's return to the MLB mound has coincided with a massive uptick in his cutter usage. In fact, over his last three starts, Rocker is throwing his cutter more than any other pitch, while also removing his slider completely and leaning into his curve more often.
Kumar Rocker Pitch Mix
You could conclude that Rocker turned his slider into a cutter, but these are drastically different pitches and he uses them in different ways. His slider is 84.1 mph with almost two inches of horizontal movement and nearly four inches of drop, which amounts to almost 41 inches of drop when you factor in gravity. Meanwhile, the cutter is nearly 91 mph with just over two inches of horizontal movement and just 28 inches of drop, when accounting for gravity.
Although there is some overlap in Rocker's approach with the pitches, it's mainly in locations. He kept the slider low in the zone to both righties and lefties, which is how Rocker uses the cutter; even though he will throw some cutters up in the zone to righties more often than to lefties. He keeps both pitches glove-side, but perhaps has better feel for the cutter because he throws cutters in the middle of the zone to righties (not outside or inside) just 24% of the time, but that mark was 33% on the slider.
That feel argument has more legs when you look at his zone and strike rates as well. Against righties, Rocker has a 61% zone rate and 81% strike rate on the cutter. He pounds the outside part of the strike zone against righties, up or down, and has gotten a 17% called strike rate. His slider had just a 44% zone rate to righties and a 67% strike rate with a sub-13% called strike rate. Yet, his slider did miss more bats against righties and was a strong two-strike pitch with a 28% PutAway rate, which measures how often a two-strike pitch leads to a strikeouts, so I don't think Rocker should abandon the slider altogether. However, his curveball does have an above-average swinging strike rate (SwStr%) to righties with a 25% PutAway Rate, so perhaps that can emerge as a solid two-strike offering for him if he does table the slider.
The most pressing issue for Rocker is finding an approach for lefties. In his career, Rocker has allowed a .333/.407/.490 slash line to lefties with a 19% strikeout rate. That's not going to fly. The slider was part of that problem. Even though he had a solid 17% SwStr% on the slider against lefties, it was not successful as a two-strike pitch, posting just an 11% PutAway Rate and a 19% chase rate in two-strike counts, which was 39th percentile. Lefties also crushed the slider to the tune of a 50% Ideal Contact Rate (ICR).
Meanwhile, Rocker's cutter has a 30% SwStr% to lefties this season. Yes, 30%! While posting a 31% PutAway Rate, 31% two-strike chase rate, and 44% ICR. It's a better pitch to lefties in every way, shape, or form. He ties them up down-and-in with the offering and is able to both use it to get ahead in the count (70% first pitch strike rate) or put a hitter away. Rocker can now lead with the cutter against lefties, while mixing in the four-seam fastball, sinker, curve, and a few changeups. If that can make him even average against lefties, that's a huge win. Then he'll attack righties with his cutter, sinker, and curve and, hopefully, mix back in the slider there as well.
For the first time in a long time, I can see a path forward for Rocker here, and I'd be adding him in deeper formats to see if he can build on this.
Michael Soroka caught my attention last time out with a 10-strikeout performance against the Dodgers, and while that performance appeared flukey on the surface, I started to dig into what the right-hander has been doing of late. Since May 17th (seven starts), Soroka has a 4.58 ERA but ranks 24th in baseball among starting pitchers with a 3.29 SIERA. He also ranks 29th over that span with a 20.7% K-BB%, so is it possible that we could be on the verge of a hot stretch for Soroka?
In order to determine that, we need to dig into what he's doing differently.
Alex Chamberlain's Pitch Leaderboard
As you can see from Alex Chamberlain's Pitch Leaderboard above, Soroka has begun to dial back on his four-seam usage and started to lean into his sinker more than at the start of the season. He has also totally abandoned his modestly used slider and just turned that usage (and more) to his solid curveball. So, should this work?
For starters, as you could likely guess, the sinker has been a more predominantly used pitch to righties. Over his last seven starts, Soroka has gone 49% four-seam and 4% sinker to lefties but 34% four-seam and 24% sinker to righties. In his first three starts of the year, he was 43% four-seam and 14% sinker to righties, so this is a noticeable change. And a good one.
Soroka uses the sinker inside to righties 64% of the time, leading to just a 29% ICR and 65% groundball rate. He doesn't get many swings and misses on it, but it ties up righties and leads to tons of weak contact. It also keeps hitters from sitting on the four-seam as much. Over his first few starts, before the uptick in sinker usage, Soroka was throwing his four-seamer inside 29% of the time and up in the zone 58% of the time. Over his last seven starts, that inside rate has fallen to 21% and is even just 16% of his last five starts. Since he has the sinker to keep righties honest inside, he can attack with his four-seam all over the strike zone. That has led to an uptick in PutAway rate (albeit a small one) but also a jump from a 14.3% SwStr% to a 17.4% mark against righties. Most importantly, the ICR on his four-seam fastball against righties has fallen from 50% early in the season to just 20% over his last seven starts. That's a HUGE improvement thanks to the added emphasis on the sinker.
Additionally, Soroka has tried to use the four-seam less in two-strike counts to righties. Early in the season, he was throwing the four-seamer 37% of the time in two-strike counts to righties, but that has fallen to 26% of the time over the last seven starts, and he didn't throw a single two-strike four-seam fastball to a right-handed hitter in that 10-strikeout game against the Dodgers.
Instead, Soroka is using his curve nearly 29% of the time in two-strike counts to righties over these last seven starts, which is an uptick from his early-season marks. On the season, that pitch has a 15% SwStr% and 34% PutAway Rate overall and a nearly 20% SwStr% and 39% PutAway rate against righties. Leaning into it more, even if it's just marginally, makes tons of sense.
Lastly, you can see from Alex Chamberlain's pitch leaderboard that Soroka has also slightly raised his arm angle overall, including raising it almost two degrees on his curveball and nearly four degrees on his four-seam fastball. While that hasn't really helped his four-seamer, it has given him a more drastic vertical approach angle on the curveball (in addition to 1.2 mph more velocity), which I think is helping the curve perform even better.
At the end of the day, I think the curve is a crucial pitch for Soroka, and one that helps him against all hitters. Leaning into it more raises his floor. The reliance on the sinker clearly helps him against righties, and I think he'll be good for fantasy teams against right-handed-heavy lineups. I'm just not sure he has enough other than the curve when he faces a team loaded with lefties.
We got another exciting MLB debut on Tuesday when Chase Burns took on the New York Yankees in Cincinnati. For three innings, we saw a debut so dominant that it brought images of Stephen Strasburg to mind. Burns struck out the side in the first, struck out the side in the second (around a two-out single), and retired the side in order in the third with yet another strikeout. However, things soured a bit in the fourth.
Ben Rice took a middle-middle slider and hit it out of the park, and then Aaron Judge followed with a single. Burns retired the next two batters before Jazz Chisholm Jr. singled and Anthony Volpe tripled in two runs. To his credit, Burns was able to recover in the fifth inning, but that one fourth inning was a good lesson that MLB hitters will punish even the smallest of mistakes. So how does Burns' arsenal stack up at this level?
For starters, the four-seam is not as electric as you'd hope. He averaged 98.1 mph on the pitch with a tremendous 17.9 inches of iVB, but also had a mediocre 6.4 feet of extension and a mediocre attack angle. If you look at the Pitcher List graphic below, it's a pitch that Burns tries to keep up in the zone, which we like to see, but it isn't as flat as the typical fastball that succeeds up in the zone.
He did get six whiffs on his four-seamer, but the 10 foul balls (and the chart below) also tell me that the pitch is more hittable than we'd think at that velocity and his command of the pitch needs to improve a bit. Too many four-seamers, especially to righties, were over the middle of the plate. That may work in the minors, but that's not going to lead to many swings and misses at the big league level. This has a bit of a Jackson Jobe feel where the four-seamer may have looked dominant in the minors but will be a bit less impactful in the big leagues where almost everybody can hit high-end velocity.
The big pitch for Burns was a plus slider that was 89.4 mph with a tight 5.3 inches of horizontal movement and 33.6 inches of drop, when accounting for gravity, which is slightly more than most sliders at that velocity. He used the pitch to both righties and lefties, but his command of the pitch was far better to righties. He was able to keep the pitch middle-away, and while I do like that he'll throw the slider backdoor to lefties, I didn't love that some of them leaked out over the plate, like the one Ben Rice hit out. The slider had six whiffs and a 37.5% CSW and 60% chase rate, so there's a lot to be excited about there.
Burns also mixed in eight changeups, which he throws exclusively to lefties. The pitch was better than I expected, with just a 25% zone rate but a 75% strike rate thanks to a few swings and misses outside of the zone. However, there were a few that got away from him up in the zone (do you sense a pattern here?), so we'll need to see how the command of that improves.
At the end of the day, Burns, like most talented rookies, is going to put together some dominant stretches and then also have some rough patches. He has a good fastball and an elite slider, but that's just has two pitches for right-handed batters, unless he begins to use that curve far more. The four-seam is fine against lefties too, but the slider is less impactful due to some command issues, and the changeup is a solid third offering to lefties but one that also has some inconsistent command.
Perhaps that was the adrenaline of the first start, but it's also worth noting that many of the Yankees' better hitters had good swings the second time they saw Burns. He's going to need to keep developing his sequencing and refining the command of his arsenal to avoid big innings, but he needs to be added in all formats and should be started next week against a Red Sox lineup that figures to still not have either Alex Bregman or Masataka Yoshida.
At a time when the Braves desperately need somebody in their rotation to step up and fill the void left by Chris Sale's injury, they may already have a solid option in Grant Holmes. The right-hander has stepped up his game over his last eight starts, posting a 2.96 ERA, 1.20 WHIP, and 20.1% K-BB% in that span. His strikeout upside has also ticked up of late, and he ranks 8th in baseball among starting pitchers in K-BB% since May 20th (six starts) with a 24.3% mark. So what has changed, and how believable is this?
As you can see from Alex Chamberlain's Pitch Leaderboard above, the easy changes we can spot are a reduction in four-seamer usage, an increase in slider usage, and the total elimination of his change and sinker, which were both little used anyway.
Right from the start, we can support the reduction in his four-seam fastball use. It grades out as a below-average pitch according to PLV, posting a below-average strike rate and just a 6.6% SwStr%. It also gives up a 55% ICR, so it gets hit hard and doesn't miss bats. That's not a pitch we want a pitcher we like to be using. Holmes had also lessened up on his cutter usage in late May and early June, but he threw 25% cutters in his last start, using it to both righties and lefties, throwing it 70% of the time early in the count to righties. On the season, the cutter is a much better strike pitch for Holmes, but also allows just a 32% ICR overall and 29% mark to righties, so it would be a positive development for him if he started using this cutter more as his early fastball.
We can also see that Holmes has dialed up his slider usage, going from 28% usage in March/April to 44% so far in June. While it's primarily a two-strike pitch for him, he has thrown it early in the count 49% of the time on the season and has an above-average first pitch strike rate on it. It's a huge strikeout pitch for him against righties, with a 37.4% two-strike chase rate and 31% PutAway rate to righties to go along with a 27% SwStr% on the season.
What's been interesting is seeing him increase the usage to lefties of late. On the season, the slider has a solid 16% SwStr% to lefties but also just a 29% ICR, so it doesn't get hit hard at all. He does a good job buying it low but doesn't exclusively get it inside to lefties, sometimes throwing it on the outside corner, which has led to soft contact. In his first eight starts of the season, he used the slider 23% of the time against lefties, throwing it low in the zone 80% of the time and outside just 23% of the time. It posted a 16% SwStr%, and 36% ICR against lefties, which are solid numbers. However, over his last eight starts, he has used the slider nearly 27% of the time to lefties but thrown outside over 40% of the time. That has decreased its effectiveness in two-strike counts, but led to a 21.4% ICR while keeping the same SwStr%.
Considering Holmes has an 84th percentile PutAway Rate against lefties with his curveball, we don't need him to get swinging strikes with his slider against lefties too. The slider can now induce weaker contact, and the cutter could potentially do the same if he leans back into it more. That means that this version of Grant Holmes can use his cutter early in the count to righties, with some four-seam mixed in, and then turn to the slider for swinging strikes, while using the cutter and slider for strikes and weak contact against lefties, and then turn to the curve for swinging strikes. It's still not an ideal setup because you have a pitcher who is hiding his four-seam fastball, but I think this is a profile that can work if Holmes brings that cutter back in more regularly. If he doesn't, I would be wary of him going forward.