Statistical projections have a notable margin for error, and a lot of that is due to variance that they account for.
One big cause for variance is a player tinkering with his profile. Development happens at any time, and with more organizations exhausting resources to help any player get better, we’ve seen progression become even more non-linear.
For pitchers, an altered pitch mix can often be the tipping point in terms of them maximizing their potential. Gerrit Cole, Kevin Gausman, Charlie Morton, and Zach Plesac are among the several recent examples to fit into that bucket.
So, which starting pitchers are the best candidates to improve with an altered pitch mix? This post kicks off the first part where we rank 25 pitchers, in order of least intriguing to most intriguing.
All Statistics via Baseball Savant and Fangraphs
#25: Alex Cobb, Los Angeles Angels
With a 5.05 projected FIP from Fangraphs and FIP over 4.80 in each of his past two full seasons, Alex Cobb isn’t the type of pitcher that is going to draw a lot of headlines, but that didn’t stop the Angels from trading prospect Jahmai Jones to the Orioles for his services.
Now, the overall numbers don't tell the whole story about Cobb’s arsenal. His splitter, which generated a 36.2% whiff rate in 2020, is a fantastic pitch. The problem is his sinker, which doesn’t generate whiffs and yielded a 54.1% hard-hit rate allowed this past season. In fact, Cobb’s increased usage of his sinker in 2017 correlates with a decrease in effectiveness, which is noteworthy.
By adopting a similar mentality to Masahiro Tanaka, who realized who couldn’t win with his fastball and relied primarily off of his splitter, Cobb can likely increase his effectiveness. It won’t be a fancy profile and he still likely will post FIPs in the mid 4.00s doing so, but even a slight decrease in FIP would make him potentially a two-win pitcher depending on his innings total, which would certainly help justify the Angels’ investment in him.
#24: Mike Minor, Kansas City Royals
Speaking of pitchers changed teams this offseason, Mike Minor earned a two-year, $18 million contract from the Royals this offseason, which was above expectation. Still, for a pitcher with a 2.5 fWAR projection, that is pretty fair value.
Minor’s xFIP projections have not matched up with his FIP counterparts in recent years, and a lot of his value comes from eating innings. Meanwhile, his average fastball velocity decreased 2 MPH this season, and his slider has decreased in effectiveness in every season.
Notably, his velocity on the pitch continues to go down, and with his fastball velocity moving downward, it serves its purpose less- it’s supposed to be a cutter. Going to more of a traditional slider would complement his changeup and curveball, two pitches with a 34.7% whiff rate in 2020, and help combat the decrease in velocity. This would help him make good on his projections and new contract, rather than seeing his fly-ball heavy mentality (even in Kansas City) catch up to him.
#23: Zac Gallen, Arizona Diamondbacks
A rising star for the Diamondbacks, Zac Gallen has a pretty complete arsenal that complements his vertical fastball well, primarily an excellent knuckle curve:
Yet, there is another pitch that Gallen has that is extremely effective- his changeup. His changeup averages 10% more than average, and has a career whiff rate over 40%. If he threw it more than 19% of the time, rather than a cutter that is his least effective offering, he could build a dominant overall arsenal. Then again, he might already be on his way to doing just that with his current pitch mix, so I’m just excited to watch him pitch this season.
#22: Aaron Civale, Cleveland Indians
Speaking of pitchers with elite changeups and curveballs, Aaron Civale has had excellent numbers with those two pitches (whiff rates over 35%), albeit in small sample sizes.
Most sinker-reliant pitchers utilize a changeup as a secondary offering, yet he only threw it 9% of the time last season, while his curveball, which generates plus vertical movement and plenty of whiffs, is used less than his cutter. Heck, his slider has had more success than his slider, which may be due to the velocity differential.
Right now, Civale doesn’t miss bats at an above-average rate. Increasing the usage of his changeup and curveball significantly, and toning down on his cutter, could allow him to be the pitcher Cleveland needs after trading away Carlos Carrasco this offseason.
#21: Kyle Gibson, Texas Rangers
With a 0.1 fWAR in the shortened 2020 season, it is safe to say that Kyle Gibson did not meet expectations in his first season of a three-year, $28 million deal with the Rangers.
Every year of his career, Gibson has allowed an xwOBA over .360 on his sinker. Meanwhile, his slider, curveball, and changeup have generated whiff rates over 30% annually. Those two facts do not coincide well with the fact that he continues to rely primarily on his slider.
Similarly to Cobb, Gibson would benefit from the Masahiro Tanaka treatment. He has three effective off speed pitches, so he has more than enough variety to be an off speed-reliant pitcher. This has been a recommendation that many have had in the past, and with his sinker rates slowly decreasing per year, there is a chance this all comes together as he heads into his age-33 season!
#20: Spencer Turnbull, Detroit Tigers
I try to be lenient with sinkers, as, a lot of time, they are thrown because the pitcher doesn’t have the “pure stuff” to throw a four-seam fastball.
This doesn’t apply to Spencer Turnbull, however. He has been able to get by with a four-seam fastball despite it having a poor movement profile, which may make sense with his slider, changeup, and curveball generating above-average vertical movement. Yet, he’s throwing his sinker as much as his slider, his secondary offering?
Turnbull gets a lot of velocity separation from his fastball, slider, and curveball. Thus, having those three pitches be his main three offerings, in addition to adopting a changeup to replace his sinker, would appear to be optimal. This would allow him to rely more on his softer pitchers, in addition to a fastball that has overachieved expectations up to this point. With the Tigers looking for future starters to complement Matt Manning, Casey Mize, and Tarik Skubal, an altered pitch mix for Turnbull could give them another asset to build around.
#19: Dylan Cease, Chicago White Sox
Dylan Cease is a great example as to why using raw spin rate to judge a pitch is rather short sighted. He ranks in the 97th percentile in fastball velocity and 94th percentile in spin rate, per Baseball Savant, but his xwOBA allowed on his fastball has sat around .400, and in terms of run value, it has been one of the worst pitches in the MLB during that span.
Despite his velocity and spin rate, Cease’s fastball doesn’t work up in the zone. Why would this be the case? Well, it generates below-average vertical movement, and also just 75% active spin. Thus, his spin rate isn’t actually translating to results.
Cease, however, generated whiff rates over 31% on his slider and changeup. Since his slider has elite vertical movement, it would appear to be the pitch he should rely on. In other words, there is no reason to continue to throw his fastball over 47% of the time. The White Sox are counting on him to fill a spot in the back of their rotation, and if he continues to post subpar K-BB ratios, that won’t happen. Less fastballs should at least help him get over the gopher ball curse.
#18: Brandon Bielak, Houston Astros
Speaking of raw fastball spin rates, Brandon Bielak ranks in the 70th percentile in that regard, but he also does so with below-average vertical movement and just 84.9% active spin. In his first season in the big leagues, that fastball allowed a 47.9% hard-hit rate and .438 xWOBA, which is no bueno, to say the least. On the other hand, his changeup, his secondary offering, generated a 43.4% whiff rate, while his slider showed promise.
Less fastballs and more focus on his horizontal pitches should help Bielak, who was productive in the minors, generate more whiffs, induce more ground balls, and allow less hard contact. Hopefully, doing so would allow him to be a productive pitcher for the Astros, who could attempt to use him in a hybrid role.
#17: Jon Gray, Colorado Rockies
Unfortunately, I’m not sure Jon Gray’s problem can be fixed until he gets out of Colorado.
Gray’s low-spin, horizontal fastball is a good fit in Colorado. Yet the pitch has been rather ineffective in recent years, while his slider (41.2% whiff rate) and curveball have continued to be productive.
As we know, playing in Colorado surpasses spin, which is likely why Gray still throws his fastball 50% of the time. A free agent after the year, he should find himself with a more progressive organization and away from Coors Field, which would figure to mean fewer fastballs and more breaking balls. If that’s the case, he could end up being one of the better values in the upcoming free agency period.
#16: Mitch Keller, Pittsburgh Pirates
Generally batted-ball and home run luck is very fluky, and that is hopefully the case for Mitch Keller, who has a career 10.46 K/9, but a .380 BABIP allowed and a 1.29 HR/9.
However, Keller may be an exception. His fastball has above-average “stuff”, but his poor command of the pitch (it generally sits in the middle of the zone) has hurt him. Right now, he is throwing his fastball more than half of the time, but what if he dials it back, particularly if he can’t develop better command? His slider has been rather elite in terms of inducing whiffs (47.1% in 2019), and something resembling more of a 50/50 split could allow him to miss even more bats while not allowing such easy hard contact.
A pitcher with his pure “stuff” has all the makings of a frontline starter. Unless his fastball command improves (a la Corbin Burnes), it is time for Keller to put his elite slider to the test. As we’re starting to see, it might be more than okay to have a slider be your #1 offering, and there is nothing to suggest that cannot be the case for Keller, particularly when command (breaking balls can sometimes lead to higher walk rates) is already his main issue.
#15: Dylan Bundy, Los Angeles Angels
Last offseason, I was incredibly intrigued by Dylan Bundy, who has elite off speed pitchers and a poor fastball. When the Angels acquired him from the Orioles, my optimism only increased.
Naturally, Bundy posted a career-best 3.75 xFIP in the shortened 2020 season. Even better, he did just what I hoped he would do: his fastball usage decreased to 33.6%, and he increased the usage of his slider and changeup.
Yet, there is still room for Bundy to grow. 25% is not enough usage for a slider that had a 50% whiff rate last season, and there isn’t much use in also increasing the usage of his curveball and sinker, which aren’t particularly effective.
Taking the next step on relying primarily on his slider will be critical in Bundy maximizing his potential. He has shown the ability to adapt to a changed pitch mix, and if he goes all-in on this slider-centric approach, he’ll set himself up to make a lot of money in free agency.
#14: Garrett Richards, Boston Red Sox
Another example of “raw spin rate isn’t the way to judge a fastball” is Garrett Richards, who has 97th percentile fastball spin, yet ranks second-worst in active spin%, has 33% less vertical movement compared to average, and failed to induce whiffs or any soft contact in 2020.
Currently, Richards is throwing his fastball 46% of the time, and he’s mostly a two-pitch slider. However, based on movement profiles and results, his slider and curveball are two vertical pitches that are elite and complement each other well. Thus, why does he need to be a two-pitch pitcher? Adopting a pitch mix similar to Bundy (33% fastball, rest off speed) would be critical for him. I hope the Red Sox, who signed him to a one-year deal this offseason, have that in mind as he looks to translate his raw stuff into above-average strikeout rates.
#13: James Paxton, Free Agent
Following the 2018 season, the Yankees traded for James Paxton hoping he’d be a frontline starter for them, and he rewarded them with a productive 3.5 fWAR. But he induced fewer ground balls, and saw his command suffer.
With the Yankees, Paxton utilized a developed cutter often, and it was a major success- whiff rate over 40%. However, with them, he also threw his fastball up in the zone, despite the fact it is a pitch predicated on horizontal movement.
Paxton should go back to working horizontally as he did during his best years with the Mariners. Doing that, and once again increasing the usage of his curveball, could make him an absolute steal on the open market. The Blue Jays are rumored to have interest in him, but what about the Giants, who have been successful with altered pitch mixes recently and play in a very big ballpark? Regardless, several teams should be intrigued by him- he posted five straight seasons with a 3.5 fWAR prior to 2020 while dealing with injuries, after all.
All of these pitches have significant room to grow, whether it be less fastball usage, throwing a better pitch more often, or changing where they locate their pitches. I’m very intrigued by Paxton working more horizontally while also having a developed cutter in his arsenal, and it’s hard to not like the upside of Richards and Keller, who have terrific sliders that need to be used. I will be back soon to finish off this list with the top-12 pitchers who can get to the next level with pitch mix changes, but, for now, and just remember: every player has room to get better!