Discipline Delta: Hitters With Changing Plate Discipline Metrics

Hitters with improving or worsening plate discipline metrics.

A third of the way through the season, statistics become very trustworthy. With rudimentary plate discipline metrics such as strikeout rate and walk rate, the sample size needed for numbers to be meaningful is meager. We are well past that stabilization point, so it’s an ideal time to look into hitters that have changed their approach at the plate, whether intended or not.

A few leaderboards involving the plate discipline improvers and decliners tell a larger story than the simple numbers suggest. Some players may be seeing the ball better than ever while others may be pressing at the plate. These leaderboards should help us identify believable breakouts and underperformers that need to make significant alterations to their approach.

To qualify, hitters had to have a minimum of 150 plate appearances.

Strikeout Rate Improvers

This has a case to be the most important leaderboard we’ll observe. Reducing strikeouts can lead to massive changes in batted ball results and can have a noticeable impact on the rest of a hitter’s abilities.

Name 2022 2023
Ronald Acuña Jr. 23.6% 13.4% -10.2%
Gleyber Torres 22.6% 12.4% -10.2%
Luis Garcia 22.3% 12.9% -9.4%
Cody Bellinger 27.3% 19% -8.3%
William Contreras 27.7% 19.8% -7.9%
Will Smith 16.6% 8.9% -7.7%
Bo Bichette 22.2% 14.6% -7.6%
J.D. Davis 33.4% 26.6% -6.8%
Javier Báez 24.9% 18.6% -6.3%
Jorge Mateo 27.6% 21.7% -5.9%

The top two improvers are having very different seasons. Ronald Acuña Jr.’s only setback at the plate was his struggles with strikeouts, but in 2023 he’s finally learned to put the ball in play more. As someone with a lot of speed, this benefits him across the board because it gives him more opportunities to use his wheels to beat out infield hits and allows him to attain more power through increased contact. He hasn’t changed his approach at all, he’s simply just making more contact.

As for Gleyber Torres, he’s traded power for contact, and while that’s allowed him to sustain an above-average level of production, it does limit his ceiling. He’s not chasing more, but he’s making more contact on pitches out of the zone which can lead to weakly-hit balls in play, reducing his opportunities to tap into his pop.

Moving down the list, we are witnessing new versions of Luis Garcia and Bo Bichette. The former has always been a batter with zero discipline (3.5%/20.4% BB/K% for his career), but so far in 2023, he’s doing exactly what you hope for a hitter of his age. Now 23 years old, García’s swing decisions have become much smarter, as he’s massively reduced his swings on pitches out of the zone while increasing his swings on pitches in the zone. His numbers aren’t reflecting his steps forward at the plate, but his expected Statcast metrics suggest a big summer is on the horizon for the youngster.

Bichette, on the other hand, has been one of the best contact hitters in baseball since making his debut in 2019. However, his aggressiveness at the plate led to a strikeout rate (21.4% prior to 2023) that wasn’t indicative of his contact abilities. This year, he’s exhibited better coverage of the zone and has kept himself in counts by making more contact on pitches out of the zone. It hasn’t eaten into any of his power metrics and he’s on pace to surpass his stellar previous seasons.

Rounding out the list, Javier Báez is another famously aggressive hitter that has found a way to avoid the pitfalls of swinging and missing. Unfortunately, it’s come at the expense of his ability to impact the ball with any authority. Last year saw him set a six-year low in K%, and with that came his worst power production since his first full season in 2016. Now making an even more significant alteration to his plate discipline, Baez’s power production is at an all-time low. It doesn’t seem like this skillset fits his style of play, and he may need to get back to being aggressive and swinging like he’s going for the home run record to reclaim his former glory.


Walk Rate Improvers

These hitters are becoming more patient at the plate and are waiting for their pitch. For some, that means better swing decisions and better pitches to hit, resulting in improvements across the board. For others, that means a lack of aggressiveness that leads to complacency at the plate, resulting in hitters being backed into corners by pitchers controlling at-bats.

Name 2022 2023
Luis Rengifo 3.3% 11.3% +8%
Ian Happ 9% 16.1% +7.1%
Brandon Marsh 6.1% 13.1% +7%
Dansby Swanson 7% 12.8% +5.8%
Will Smith 9.7% 15.5% +5.8%
Randy Arozarena 7.1% 12.7% +5.6%
Cedric Mullins 7% 12.5% +5.5%
Mookie Betts 8.6% 13.8% +5.2%
Matt Olson 10.7% 15.5% +4.8%
Kyle Schwarber 12.9% 17.2% +4.3%

Leading the list, Luis Rengifo has completely altered his approach and it has led to complacency. He’s swinging less, which can be positive, but not when it doesn’t lead to a reduction in the swing-and-miss department, as is the case here. He should be waiting for his pitch to hit, but instead, he’s not gaining any advantage and it’s forcing him to forego trying to do damage at the plate.

On the opposite end of that spectrum, Brandon Marsh is walking more than ever and it’s paying off. He’s swinging and missing less often because he’s waiting for his pitch and attacking it when it arrives. It’s led to a significant increase in hard-hit balls and has made him a more dynamic threat at the plate. While he’ll always be a guy that strikes out a lot, offsetting those whiffs with walks is a good place to start.

Will Smith is the only player to make both lists of improvers. He was already a guy with exceptional plate discipline metrics, but his gains this year make him the second-best hitter in terms of BB/K rate, trailing only Luis Arraez. It’s difficult to decide which improvement has been more impressive, but I’m mostly just dumbfounded by the fact that he’s been able to do both. He’s simply just making more contact on pitches out of the zone and he hasn’t let that impact his batted-ball metrics. He’s far and away the best offensive catcher in baseball thanks to his all-seeing eyes.

While they haven’t yet taken full advantage of their newly increased walk rates, both Randy Arozarena and Cedric Mullins should benefit massively in the stolen base department. Getting on base is half the battle when it comes to swiping bases, and these two have made the necessary adjustments to put themselves in ideal positions to perform a theft. Arozaren’s success rate in recent years hasn’t been great, but the eagerness is there and bases are much easier to steal with the new rules. Mullins has been one of the best base thieves since his breakout, and with the rate he’s reaching base, a 40+ steal season seems all but certain.


Strikeout Rate Decliners

Opposite its counterpart, this has to be the most unfortunate leaderboard for which to qualify. There’s rarely a silver lining to an increased strikeout rate and these hitters have proven that with their performance through the first couple of months of the season.

Name 2022 2023
DJ LeMahieu 13.1% 25.5% +12.4%
Michael A. Taylor 23.9% 35.5% +11.6%
Nolan Arenado 11.6% 20.3% +8.7%
Luis Robert Jr. 19.2% 27.6% +8.4%
Connor Joe 20.8% 27.4% +6.6%
MJ Melendez 24.5% 31.1% +6.6%
Ha-Seong Kim 17.2% 23.8% +6.6%
José Abreu 16.2% 22.7% +6.5%
Juan Soto 14.5% 21% +6.5%
Amed Rosario 16.6% 22.9% +6.3%


Nolan Arenado and José Abreu have been the 2023 poster children for perennial All-Stars failing to live up to the standards they set throughout their careers. The former has always been lauded for his preternatural ability to pair power with one of the lowest strikeout rates in baseball. This year, we’re witnessing the opposite. He’s sporting the lowest isolated power (.169) of his career since his 2013 debut and is striking out at the highest rate of his career. It could be due to injury, but the improvements he showed in May (18.9% K%), would still be the worst full-season rate of his career.

Age might finally be catching up with Abreu. While we’ve seen him strike out at a 22% clip in years past (most notably his MVP 2020 campaign), it never came with completely empty batted ball metrics. His swing decisions or contact ability haven’t changed at all, so it’s somewhat peculiar that we’re seeing him struggle so much. It’s almost as if he’s just not swinging hard enough. Given his track record, he’s almost guaranteed to bounce back in the second half, but I don’t think the increased strikeout rate is the culprit for his struggles in Houston.

MJ Melendez made a name for himself as a power-hitting catcher in 2022. Now playing the outfield, none of those adjectives describe him. He’s been very unlucky in the power department with just five homers on 17 barrels, but the most notable deficiency in his game this year has been the increased amount of punchouts. His plate discipline has declined across the board as he’s chasing more, making less contact, and swinging and missing more than ever. The power should come back when luck comes his way, but he’ll need to alter his approach if he wants to see improvements in the batting average department.


Walk Rate Decliners

Contrary to strikeout rate, a worsening walk rate is not inherently detrimental. Some players need to be more aggressive to fully tap into their potential at the plate. However, others can be too aggressive and won’t wait for their pitch, leading to poor swing decisions and batted ball results.

Name 2022 2023
Isaac Paredes 11.5% 5.8% -5.7%
DJ LeMahieu 12.4% 7.7% -4.7%
Garrett Cooper 8.5% 4.4% -4.1%
Mike Yastrzemski 10.9% 7.1% -3.8%
Yasmani Grandal 12% 8.2% -3.8%
Ketel Marte 9.9% 6.6% -3.3%
Manny Machado 9.8% 6.5% -3.3%
Rafael Devers 8.1% 5% -3.1%
Jon Berti 10.4% 7.3% -3.1%
J.D. Martinez 8.7% 5.6% -3.1%

Carrying over the breakout from last year, Isaac Paredes is one of the rare examples of a concerted effort to be more aggressive. While his 2022 was impressive, he was too passive and didn’t let his bat do the talking. Whether the Rays noticed that and told him to change his approach or they knew a change in his approach would be necessary as pitchers adjusted OR if it’s all just a coincidence and Paredes is becoming better all on his own, he’s been even better in 2023. He’s swinging more often without detrimental impacts on his contact or power abilities. Statcast suggests the continuation of his power stroke is undeserved, but he makes up for it by pulling the ball in the air with authority. Don’t let that reduced walk rate scare you away from another great campaign.

The only player to make both decliners lists, DJ LeMahieu has had a precipitous late-career fall-off, but his 2022 was more than solid even if it went under the radar. One of the key components of his success was displaying the best plate discipline of his career. In 2023, we’ve seen his approach pull a 180, as he’s now sporting the worst BB/K ratio of his career since his first full season in 2013. He’s been unable to make contact out of the zone and is swinging and missing more than ever. It sort of seems like he’s selling out for power, but LeMahieu is a hitter that thrives on his abilities as a contact hitter. He must return to that mold to regain his form.

I think it’s easy to explain Manny Machado’s surprisingly terrible first two months. Some early bad luck forced him to start pressing. The pressing led to an aggressive approach at the plate which resulted in fewer walks, more whiffs, and fewer hard hits which, in turn, maintained the illusions of an unlucky start. Now on the IL, Machado will have the time to get his head right. He’s still only 30, so an age-related decline is out of the question, but getting his plate discipline fixed will be the first step to a rebound.


Photo by John Adams/Icon Sportswire | Adapted by Justin Paradis (@JustParaDesigns on Twitter)

Jake Crumpler

A Bay Area sports fan and lover of baseball, Jake is a graduate of the University of California, Santa Cruz with a B.A. in English Literature. He currently writes fantasy articles for Pitcher List, is the lead baseball writer at The Athletes Hub, and does playing time analysis at BaseballHQ. Some consider his knowledge of the sport to be encyclopedic.

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