2024 Top 10 Starting Pitchers BB Rate Improvers

Background

In today’s day and age of chasing high K%, stuff+, and red lollipops, I wanted to take time to focus on pitchers that saw the strongest improvements in their BB rates in 2024. While walks are only part a pitcher’s possible outcomes, I believe pitchers can improve their “control” through various means such as approach, preparation, pitch sighting, and other means. In this article we will dive into the top 10 starting pitchers who improved their BB rate from 2023 to 2024 and looking deeper into their numbers to forecast what 2025 may have in store for these arms. To qualify for this list, a pitcher must have thrown at least 100 major league innings in both the 2023 and 2024 seasons. 

2023 Top Improvers

     To get an idea of who would have made this list last year running the same exercise, the biggest 2022 to 2023 BB improvers with at least 100 IP in both seasons were Yusei Kikuchi, Justin Steele, Adrian Houser, Joe Ryan, Logan Webb, Kyle Bradish, Mitch Keller, Logan Gilbert, Dane Dunning, and George Kirby. While not all had full seasons in 2024, Gilbert, Kirby Steele, Ryan, Webb all had strong results with Kikuchi and Keller also contributing some valuable innings throughout the season. With that, we dive into the top 10 starting pitchers who improved their BB rate year over year to better prepare you for your fantasy baseball drafts.

2024 Top Improvers

1. Nick Martinez – Martinez topped our rate of improvers with his BB% dropping from 8.7% down to 3.2% which would be the 3rd lowest walk rate out of pitchers with 100+ innings in 2024 behind Bryan Woo (2.8%) and George Kirby (3.0%). 2024 was a career year for Martinez, topping his career bests in BB% (3.2%), ERA (3.10), innings pitched (142.1), WAR (3.5), and K-BB (17.2%). Martinez was partially able to improve his walk rate by improving his zone % and FPS% to career bests at 52.8% and 67.5% respectively. For extra context since these stats will be brought up again during this article, major league average is 48.7% for zone % and 61% for FPS% according to Baseball Savant. Looking into his pitch mix changes year over year, Martinez increased the usage of his hard pitches (4S/Cutter/Sinker) from 51.8% to 60.3% while also bringing back his slider in 2024. Focusing more on different fastballs and lowering the breaking ball/offspeed pitches is one way to improve control if Martinez is able to better control his fastballs vs his other pitches. Martinez just re-signed a qualifying offer and will be under contract with the Reds for one more season with the chances of a trade at the deadline pending how the Reds season plays out.  Martinez will be primed for a starters workload in 2025 and while I do expect his homerun rates to fall closer to career rates and a regression in ERA, I’d still consider Martinez a buy vs his current Streamer projections at a 4.72 ERA. 
2. Jack Flaherty – Flaherty posted a career best BB% at 5.9% in 2024. This mixed with his K rates jumping back to peak 2018-2019 rates pushed Flaherty back onto fantasy managers radars in 2024. Flaherty ditched his cutter in 2024 and increased his fastball, slider, and curveball usage. He used his sinker and change-up as a show me 4th pitch to right-handers and left-handers respectively giving him 4 pitches to each side. Digging deeper into some of the pitch heat map visualizations on Baseball Savant, it looks like Flaherty is filling up the zone more consistently with his 4S compared to previous years. However, his zone % and FPS % were at 45.7% and 61.2% makes me think he could be in line for regression with his BB% next year. I am in line with most of his 2025 Steamer projections at a 25.2% K%, 7.6% BB% and a 3.85 ERA, but expect his BB% to go back above 9%. Do not reach for Flaherty, but look at him as a borderline top 50 SP.
3. Andrew Heaney – A decade ago in 2014, Heaney was the top prospect for the Marlins who was the main piece in the trade that brought Dee Gordon, Dan Haren, and Miguel Rojas to the Marlins. Flash forward to 2024 and Heaney is coming off one of his more productive seasons of his career, logging his highest IP (160) and WAR (2.2) since 2018. Heaney ranked tied 4th in BB% improvers in 2024 with a 5.9% BB% which brought him closer to his career BB% at 6.9%. In 2023, his first year with the Rangers, Heaney’s BB% shot up 3.3% to 9.4%, which was the highest of his career, so a normalization to his career rates helped Heaney get a spot on this list. Keeping his BB% rate in line with his career rates will be needed for Heaney to remain successful as his K% and fastball velocity trend down. I’d expect Heaney to be a similar pitcher to who he was in 2024, a back-end starter who will throw 160+ innings. For shallower leagues, recommend using Heaney as a streamer while in deeper leagues could be a late round flier if needing innings and Ks, but keep an eye on where he signs this offseason.
4. Jake Irvin – Irvin was a constant in a young Nationals rotation during the 2024 season who held it down during the first half throwing 100+ innings of 3.49 ERA before getting hit with a 1.88 HR/9 and 5.90 ERA in the second half. This year, Irvin’s BB% improved by 3.4% down to 5.9% and slots right between Mitch Spence and Jose Berrios in 2024 BB% rankings. Irvin introduced a cutter into his primarily 4S, curve, sinker mix to become more of a 4-pitch pitcher. This can allow him to attack hitters more aggressively with his different pitches, especially vs left-handed hitters which Irvin has ditched his sinker in favor of his cutter in 2024. Steamer has Irvin projected to keep most of his BB% gains in 2025 at 7.6% which I think he has a chance to beat given his minor league BB% rates were around 6.8% before AAA in 2023 when they introduced the ABS system. How, without an improvement or increased usage to a current pitch such as his changeup or an introduction to a new plus whiff pitch, there is a lack of upside and project Irvin to finish 2025 somewhere in the middle between his 2023/2024 results with 160+ innings and mid 4s ERA. Recommend keeping Irvin as a weekly streamer in 2025.
5. Blake Snell – Snell is one of my favorite pitchers in the game and is someone I’d love to treat to an ice cream one day courtesy of DoubleScoopBaseball. Snell is an interesting pitcher for this article as he consistently has one of the highest BB% in the league and is still able to maintain success due to how good he is at striking hitters out and limiting base hits/homeruns. In 2023, when Snell was the National League’s CY young award winner, he had a league high 13.3% BB%. In 2024, he was top 5 in BB% improvers among starters with 100+ IP while also increasing his year over year K% and batting average against. His BB% specifically was back in line with his career averages and did not fluctuate throughout the year which was a tale of two halves. With his recent signing with the Dodgers, I’m expecting Snell to keep his momentum as he should have a normal spring training and has the potential to be a top 5 SP. Currently ADP from NFBC has him going as the 17th pitcher, I wouldn’t let him slide too far and would take him as a top 10 SP in 2025 drafts.
6. Tanner Houck – Houck has been an intriguing arm since coming up with the Red Sox in 2020 and 2021, posting K rates of 30%+ in both seasons. Looking back at Houck’s 2024 season, he posted a career best 6.5% BB%, however this also came with a career low 20.7% K%. Houck continued to evolve his pitch mix from 2023 and ramped up his splitter usage from 11% to 25% and introducing a true sweeper to replace his slider that increased his horizontal break by 5 inches with around half inch less vertical break without sacrificing velocity. He also dropped his 4-seam completely while only throwing his cutter 1% of the time in 2024. On top of the pitch mix change, Houck had a career best zone % and FPS % at 53% and 65%, both above league average marks according to Baseball Savant. Simplifying a 5-pitch mix into a primarily 3-pitch mix in combo with attacking hitters more aggressively is a good recipe for repeating his control gains going into 2025. On top of that, Houck gets a ton of groundballs, so if he can continue to tinker with his pitches, such as continuing to develop his cutter, it will give him another weapon against lefties and possibly a better way to keep hitters off balance and generate more Ks. Houck currently has an NFBC ADP lower than Nick Pivetta, Bowen Francis, Nathan Eovaldi, Brandon Woodruff, and Mackenzie Gore, of which I believe Houck has the chance to outperform except Gore due to Gore’s upside. 
7. Nick Pivetta – Pivetta just wrapped up his 8th major league season and like many on this list, is coming off career best BB%. Looking at how he was attacking hitters, he jumped to a 68.6% FPS% in 2024 which would put him in the top 10 of pitchers who had 100+ innings pitched. All in all, results did not change a ton for Pivetta, with his ERA increasing a hair from 4.04 to 4.14 year over year. If looking for a silver lining, his SIERA was 3.31, indicating he pitched better than his ERA. He kept most of his K% gains from 2023 which can give hope for an eventual breakout if he signs somewhere with a pitcher friendly park which could help improve his homerun rate which was bottom 5 in the league among starters. I’m still worried he is too predictable against LHB and RHB which could lead to him getting hit hard, however his 4S, Sweeper, Curveball combo could still be good enough to keep his strong K-BB results he has posted over the past two years. Keep an eye on where Pivetta signs, if going to a pitcher friendly park he could be an interesting buy, otherwise I’d expect more of the same from Pivetta.
8. Ranger Suarez – Suarez originally broke out on the fantasy radar in 2021 posting a ridiculous 1.36 ERA in 106 innings. In the 3 seasons since he has posted a more modest 3.74 ERA and a 3.70 FIP, which is very serviceable in Fantasy leagues. One sign pointing to his improvements in BB%, is his career best in FPS% at 64.5%. While not an elite rate, it does give me confidence that he is continuing to improve the way he is mixing his pitches. This goes to show as he increased his curveball usage when trying to throw more “get me over” strikes in 0-0, 1-0, 2-0 counts. Suarez has 5 pitches that he throws over 10% of the time, of which his curveball and changeups run whiff rates of 30%+. If there is one knock I have against Suarez, it’s that his velocity is down across all his pitches in 2024 but going into his age 30 season I could see a bounce back in some velocity. Suarez is the 105th ranked SP in terms of ADP by NFBC. Let Suarez fall in your drafts but try and grab him as he has a great 5-pitch mix and should get a good number of wins behind the Phillies offense which I feel confident will lead to top 50 SP results.
9. Charlie Morton – One of oldest active pitchers in the MLB in 2024 behind Justin Verlander and Jesse Chavez, Morton is still finding ways to improve his game and finding a way on to this list. Unfortunately, even with the improvement, the 9.3% BB% in 2024 brought him back in line with his career average 8.6% BB%. Morton has always been slightly below average in his career with FPS % with his 2024 rate equaling his 59.3%. Morton’s zone % remains below his career averages in 2024 and at age 42 and coming off a season with a 9.3% BB%, I do not expect any signs of improvement for Morton. Paired with declining velocity, lowering K rates, and uncertainty on where he may sign in 2025, I would look elsewhere deeper in drafts. Even if desperate for innings in deeper leagues, I would take the shot on other veteran arms or younger arms who could earn rotation spots in season.
10. Corbin Burnes – Hopefully this post isn’t needed to convince you that Corbin Burnes is worth drafting. Burnes has been one of the top pitchers over the past few seasons and finds himself as number 10 on our list. Burnes zone % was relatively similar to 2023, but he was able to increase his first FPS% to 63.9%, a good improvement over his career rates of 60.2% Similar to Suarez, this number does not jump out, but getting ahead of more hitters and putting yourself in pitchers count puts a pitcher in a better position for success. To me this also could indicate that this pitcher is either more confident with their pitches, attempting to be more aggressive in the zone, or finding ways to more consistently land their 0-0 breaking balls and off-speed pitches. Fun fact about Burnes 2024 season, he increased his 0-0 curveball usage from 19.5% to 30.4%. Burnes should be in a good position to keep his BB% gains in 2025 and do not expect too much regression here as he continues to improve going into the 2025 where he will be 30 for the regular season. His velocity on his cutter/sinker were the highest since his 2021 season and his curveball, slider, changeup are all plus pitches. Burnes will be a top 10 SP taken off the board. Feel comfortable taking him as your #1 SP on to your team as he has been one of the most dependable pitchers over the past few seasons with no signs of slowing down. 

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