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Now that we're a couple of months into the season, we have the ability to track month-to-month changes to see if any players are making adjustments. Sometimes these changes can manifest in a clear difference in results, while other times we can start to see some changes under the surface that have not yet shown up in the box score, which gives us a chance to buy before an explosion in value.
When it comes to identifying pitching performance, especially in the middle of the season, I love looking at K-BB%. I'm not alone there. To me, it's just the simplest identifier of pitching performance because it looks at how often a pitcher is missing bats (a good thing) and how infrequently a pitcher is giving up free bases (a bad thing). When the pitcher is doing the good thing a lot and the bad thing not a lot, we get a high K-BB% and, most likely, a strong pitcher.
So, in this article, I wanted to look at the biggest improvers in K-BB% from April to May. Fellow RotoBaller Jon Anderson worked his magic and distilled the information into a handy chart, and you can see the top-20 names below. While appearing on this list is a good thing, it's also important to note that not all "improvers" are created equal as some could have simply started from a poor baseline. As a result, I've broken down some of the most interesting names in more detailed descriptions below, so I hope you enjoy and find it useful.
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K-BB% Change Leaderboard
Spencer Strider, Atlanta Braves
It's important to note that Strider's first start as a member of the rotation came on May 30th, so the majority of this increase is during his time as a reliever. Still, I wanted to bring him up because he's an incredibly trendy name now that he's in the Braves' rotation.
So far, in his two starts, he's allowed six runs (four earned) in 8.1 innings with 12 strikeouts and seven walks. He also hasn't been able to pitch five innings in either start, which is a bit of a concern, and, weirdly enough, his start in Coors was better than his start on the road in Arizona.
The Braves seem to be capping Strider around 90 pitches, which is not a low total in and of itself, but his early issues with control have limited his ability to go deep enough into games at that cap. If he can become more efficient than he should be able to go five innings more regularly, which would give him some win upside.
Another concern for me is that Strider really only has two pitches. Although, they are both good pitches. Even as a starter, his fastball is regularly sitting 95-96 mph and has a 33.9% CSW. He did lose command of it a bit in his last start, and he didn't get a single swing-and-miss on the pitch, which is concerning. His slider, however, has been electric with a 17.7% swinging-strike rate (SwStr%) and 38.1% CSW on the season. The slider also had an absurd 62% whiff rate in his last start against the Rockies; although, it did have a 37% CSW because he's not getting many called strikes with it, which makes sense when you look at the pitch graph of the game.
This means that Strider will need to utilize his change-up more. If he's really only using the slider as a swing-and-miss pitch and not a "zone strike" pitch, then he has to give hitters another pitch besides that fastball that he can throw for a strike. The change-up has flashed the ability to be that pitch, and he used it 22% of the time in his start in Arizona, but, unfortunately, that dropped to just four total change-ups thrown in his last start. Maybe it was just Coors Field, but that's not going to work, so you have to hope it was a one-game blip; however, he also never really used the change-up as a reliever, so it's also unclear how uncomfortable he is with the pitch.
At the end of the day, I believe in the long-term upside of Strider. However, he remains a bit of a risky proposition this year because we're unsure if his arsenal, stamina, or accuracy can transition to the rotation. If somebody in your league is all-in on him, now might be the time to try to explore offers for Strider to see if you can get high-end stable production elsewhere on your roster. I'm a little bit worried that, for the purposes of the 2022 season only, he might be too inconsistent as a full-time starter and may be best suited in a multi-inning relief role.
Yusei Kikuchi, Toronto Blue Jays
There have been a lot of smart people talking about a resurgence for Kikuchi for weeks now. After his first six starts saw him face the Yankees three times, the Astros twice, and Boston, there was a strong argument that easier competition would lead to more success for the left-hander. Only, that hasn't actually been true.
While his May stats are strong, much of that comes from his first three starts of the month, two of which were actually against the Yankees. In those two starts, Kikuchi let up just three earned runs in 11.1 innings while striking out 14 and walking just four hitters. He also looked great in his next start against the Mariners, throwing six shutout innings, while allowing just one hit and striking out six.
In his three starts since then (against the Twins, Angels, and Reds) he's allowed eight earned runs in 14 innings, while also giving up 18 hits. He's struck out 17 batters while walking just four, which is good news, but the results have been inconsistent, and I'm not sure I'm going to get in on this hype.
On the season, Kikuchi has two above-average swing-and-miss pitches. His cutter has a 16.8% SwStr%, and his changeup has a 19.8% rate. The only issue is that he stopped throwing his cutter after his April 24th start, and he's only throwing his changeup 12.4% of the time on the season.
There is a lot of love out there for Kikcuhi's slider, but it has a 12.4% SwStr%, 25.5% CSW, and 6.13 deserved ERA (dERA). Yes, it has been successful for him as a two-strike pitch, but it's also giving up a .323 batting average (.296 xBA) and a .631 slugging percentage (.568 xSLG), so it's getting hit too hard when it's put in play.
That leaves him with a four-seam fastball that has a .203 batting average against and 2.01 dERA but a .283 xBA and 13% barrel rate allowed on the season. It's still a fine pitch, but there are some warning signs with it as well. Kikcuhi did start throwing his change-up more in the last start, which is good to see, but I'd need to see that more going forward since I'm not really a huge fan of that slider right now. I think the left-hander is putting too much pressure on his 95 mph fastball to carry him, which makes me a bit nervous about his long-term value.
Nick Pivetta, Boston Red Sox
It was quite a May for Pivetta. In 38.1 innings, he went 4-0 with a 2.11 ERA, 0.83 WHIP, .187 batting average against, and 19.9% K-BB%. What's interesting to note here about his presence on the leaderboard is that the 19.9% rate isn't great on its own, but simply because his April was so bad.
Why was his April so bad? Well, for starters, his four starts were against the Blue Jays (twice), Yankees, and Twins. He also followed that up with a poor May 1st start against the Orioles where he allowed three earned runs and six hits in 4.1 innings. So what changed after May 1st?
The answer is, really, not much. At least in terms of pitch mix. Pivetta is still throwing his four-seam around 50% of the time and mixing in his slider and curve a combined 45% of the time, depending on the game. However, he has seen improved performance on all three pitches, with each pitch registering a dERA under 1.79 since that May 1st start. In April, the fastball was his best pitch with a 3.13 dERA, while the curve and slider were both over 7.50.
Part of the improvement could just be an increased feel for his pitches. We know there were many pitchers who were complaining about the new baseball at the beginning of the season, so it's possible that Pivetta simply didn't have a feel for his offspeed pitches until more recently.
We also know that his slider has been a bit different in May. While the sample size is obviously just one month, Alex Chamberlain's Pitch Leaderboard shows us that Pivetta is throwing his slider almost one mph slower in May and has added more run, while reducing some vertical drop. We can also see that in this Brooks Baseball chart registering vertical movement plus gravity by month:
Perhaps this change has helped limit hard contact on the pitch, but we'll need a larger sample size to know for sure.
At the end of the day, only the slider is registering as a true swing-and-miss pitch. It has a 17.2% SwStr%, which is Pivetta's only offering over 10%. He does have a 35.1% CSW on the curve, but that's thanks to a 26% called strike rate. The curve is also allowing an 11.8% barrel rate since May 1st, while the fastball is giving up an 8.2% rate, so I can't help but feel like some regression is coming.
At the end of the day, I think Pivetta's May is not sustainable, but the poor April is also misleading, and Pivetta will likely settle in as a mid-to-high three ERA pitcher with a K-BB% under 20%.
Aaron Ashby, Milwaukee Brewers
This should not come as a surprise to you, but I'm a big Aaron Ashby fan and you should be too. He has two legitimate swing-and-miss pitches in his slider (20.3% SwStr%) and his change-up (18.5% SwStr) and pairs that with two pitches that he locates really well for strikes in his sinker (29.9% CSW) and curveball (48.2% CSW). It's a complete arsenal, and I love how it's constructed, which you can see here on the Spin Direction Graphics:
The sinker and change-up pair well with one another because they approach the batter at a similar trajectory but seven mph different and the change-up has more arm-side run. Those two pitches are also near-perfect mirrors of the slider and curve, which also approach the batter at similar angles, but with a three mph velocity gap and far different movement profile. It consistently keeps hitters guessing.
Since moving into the rotation, Ashby has all but scrapped his fastball and is actually using his change-up more, throwing it 25.1% in May after using it 18.7% of the time in April. We discussed above how it misses bats and pairs well with his sinker, and it also has a 3.17 dERA and .200 batting average against, so using it more is a great thing.
I think Ashby is the breakout future ace on the Brewers staff that many people believed Eric Lauer was. I'd be doing whatever I could to acquire him. Of course, I could have skipped this whole section and just showed you the pitch below and you'd be trying to acquire him anyway.
Vladimir Gutierrez, Cincinnati Reds
Don't be fooled by this. An 11.8% K-BB% is not particularly good, but he was just so bad in April. There is nothing in the underlying metrics that suggests anything fantasy-noteworthy.
This is basically the same for Zach Thompson and Cal Quantrill. I think both of those guys are streamable in the right matchups, but neither should be viewed as an option you have to hold on your roster. Thompson has a 4.31 xFIP and 4.50 SIERA. He's inducing just a 9.9% swinging-strike rate, and his May was propped up by two good starts against Cincinnati before the Reds offense really got going. Quantrill, similarly, has a 4.90 xFIP and 5.01 SIERA. He misses even fewer bats, with a 7.0% swinging-strike rate, and just gives you nothing that's particularly useful for fantasy aside from a 1.19 WHIP which is not even that great.
Tony Gonsolin and Tyler Anderson, Los Angeles Dodgers
I'm going to lump these two in together because it's possible that only one of them remains in the Dodgers rotation. With Clayton Kershaw set to return from his rehab stint, it looks like Mitch White will be bumped to the bullpen soon. However, Andrew Heaney is also reportedly close to going on a rehab assignment, which means that his return would force the Dodgers to go to a six-man rotation or move one of these two pitchers to the bullpen.
On the season, it's actually been Anderson who's been slightly more impressive. He has a higher SwStr% at 15.3% and a higher CSW at 31.2%. He also has the superior K-BB% because of his minuscule 2.7% walk rate so far this season.
A big change for Anderson this season has been relying on his change-up more, throwing the pitch 31% of the time now (his most-used pitch) rather than 24.6% last year. It makes sense since his change-up has a 26.4% SwStr%, 32.9% CSW, and .108 batting average against. It's the best individual pitch that either guy throws. In fact, if you rank the pitches by CSW, Anderson actually has four of the top five pitches between these two, excluding Gonsolin's curveball, which has an impressive 47.6% CSW thanks to an almost 40% called strike rate.
However, while Anderson's arsenal has been more geared towards swing-and-miss, Gonsolin's allows much weaker contact. Every single one of Anderson's pitches has a launch angle allowed of over 16.7-degrees, which means that when hitters do make contact, it can be more damaging contact. His four-seam in particular has allowed a 17.9% barrel rate, while his sinker has posted an 11.8% barrel rate. This is part of the reason why Gonsolin has a better dERA at 2.08 compared to Anderson's 3.27.
There is still time left until Heaney comes back, and both of these pitchers deserve to be in your lineups. It's also entirely possible that Walker Buehler or Julio Urias (who both don't look 100%) may have a stint on the IL which allows both of these arms t0 remain in the rotation. However, if push comes to shove, I believe Anderson will stay in the rotation and allow Gonsolin to move back into a multi-inning relief role since the Dodgers have used him there before and he's shown that he's capabale of rewarding their trust, while Anderson has almost always been a starting pitcher and the Dodgers may feel more comfortable allowing him to stay there.
Robbie Ray, Seattle Mariners
I've written a lot about not buying into Ray for this season, so I'll be brief here because we can all accept my bias. He did miss more bats in May, which is a good thing, upping his strikeout rate to 33.3% from 20.8%. He also "cut" his walk rate down to 7.15, but that's still much higher than he was putting up last year. More troubling is that he continues to allow lots of hard contact and allowed a 19.4% HR/FB rate in May with six home runs allowed in 30.1 innings. That's part of the season he also had a 5.34 ERA in May.
Remember that Ray had a 90.1% left on base rate last year and still allowed a 9.8% barrel rate over the whole season. He was attacking the zone and daring hitters to hit him. Well, they are now. Yes, the strikeout rate going up is nice but he's still allowing far too much hard contact for my liking and back to walking a few too many hitters. I'm not buying any kind of resurgence here and think he remains a low-to-mid-four ERA pitcher with solid strikeout numbers for the remainder of the season.
Trevor Rogers, Miami Marlins
I covered Trevor Rogers in a recent deep-dive video, so I'd love for you to check out my thoughts there.
Framber Valdez, Houston Astros
I covered Framber in my Pitchers With New Pitches series, so check that out because I'm a believer in what he's doing.
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