Real Time Analytics

Sample Size Watch, Part Two: Walks

Jake Roth-USA TODAY Sports

Wil Myers doesn’t walk, he trots. Which hitters have added the base on balls to their skill set, and who else is on the decline?

When we examined strikeout rates in Part One of this series on sample sizes, the baseball world was still very much in flux. As we know, strikeouts are one of the first statistics to stabilize for hitters at a sample of just 60 plate appearances. Back when most players were just reaching 60 PA, we could still attribute season-opening slumps to bad luck or withhold our judgment on teams at the top of their respective divisions. 

Now, however, as we begin looking at the not-so-sexy stat that is walk rate (BB%), there is a different mood around the league. We ask, “Are the Yankees for real? Are the Rockies for real? What’s wrong with the Cubs?” That is to say, nearly one quarter of the long MLB season is complete and the postseason picture, while still far off on the horizon, is marginally clearer here in mid-May. 

Statistically, our level of certainty for most metrics is still pretty low. Walk rates, like strikeout rates, are an exception. For hitters, walk rate will stabilize at about 120 PA. At this threshold, upgrades and downgrades in patience may be attributed to skill rather than small samples or noise. With that in mind, here are three players who have improved markedly in their walk rates and three whose discipline has declined.


The StatCast Stud – Miguel Sano

Image titleKevin Jairaj-USA TODAY Sports

Walk Percent (BB%)
Plate Appearances (PAs)

Everything about Sano, the 24-year-old third baseman of the Minnesota Twins, screams “power.” As a prospect, he displayed 80-grade skills in both raw power and arm strength. After a promising debut in 2015 (150 wRC+), Sano slipped last season to just slightly above the league average in offensive performance (107 wRC+). Regression was not unexpected; his BABIP as a rookie was unsustainably high (.396). However, Sano also saw his walk rate drop by a sizable margin in his sophomore season, from 15.8% to 10.9%. 

This year, Sano is leading the American League in BB% and trails only Matt Carpenter across all of baseball in that category. Sano also sits atop the leaderboard in average exit velocity at a blistering 99.9 MPH, and that race isn’t close. The boosted walk rate,  unbelievably hard contact, and nonexistent soft contact have Sano slashing .287/.427/.643, good for a 185 wRC+. 

MIN@TEX: Sano smashes solo home run to left-center 

(Unsurprisingly, walks hardly make it into highlight reels. It’s a good thing Miguel Sano can do this pretty often.) 

Interestingly, despite almost doubling his walk rate, Sano is only slightly more disciplined than last season. His chase rates have declined from 25.2% as a rookie to 23.7% last season and currently 22.3% (though this improvement is more significant according to PITCHf/x). Moreover, Sano is also striking out just as often; his K rate is 34.3%, just slightly better than the 36.0% he put up last year. The big difference is that he is seeing fewer pitches in the strike zone than ever before. Combine that career-low 41.2% Zone% with slight improvements in pitch recognition and a mechanical adjustment and you get a beast of a bat. His proclivity for whiffing and a BABIP (.411) that literally hasn’t been seen since the 1920s prevent him from being a near-.300 hitter, but Sano’s newly developed skill for base on balls appears to be here for the long haul.

The Hot Starter – Zack CozartImage title

David Kohl-USA TODAY Sports

Walk Percent (BB%)
Plate Appearances (PAs)

Cozart, the Cincinnati Reds shortstop with a strong defensive reputation, is currently slashing .350/.437/.608. I knew I had seen this before. I just had this hazy recollection of a hot Zack Cozart at the beginning of the 2016 season. Sure enough, in April last year, Cozart hit .361/.355/.556. That is not a typo!  Due to just a single walk and three sacrifice flies, Cozart featured an OBP lower than his batting average for more than a month. After walking just 37 times all of last year, he has already walked 20 times in 33 games played. 

Cozart’s spring surge in 2017 is in part a reflection of his dramatically improved walk rate, which has jumped from 7.3% last season to 14.1%. I considered that perhaps the usually light-hitting Cozart was walking more because Reds manager Bryan Price had him in the 8-hole, the lineup spot ahead of the pitcher. But no, Cozart has split his time between the second and seventh positions in the batting order. Kudos to Price, because the shortstop has become a completely new hitter over the past two seasons. Simply put, Cozart is more disciplined now than ever before. His swing rate is 41.9%, far below his percentage last year (47.1%) and for his career (46.5%). A free agent at the end of the season, Cozart has raised his stock thanks to a tandem of consistently strong defense and, now, emerging plate discipline.

The Three-Outcome Utility Man – Brad MillerImage title

Kim Klement-USA TODAY Sports

Walk Percent (BB%)
Plate Appearances (PAs)

What do we know about Brad Miller? Defensive versatility comes to mind. Even though the Tampa Bay Rays have exclusively played him at second base this season, he has manned every position besides pitcher and catcher over the past three years. Emerging power with an all-or-nothing twist just recently became a trademark of Miller’s. With his bat, Miller notched a career-high 30 home runs last season and a career-worst K% of 24.8%. This year, he ostensibly added the third true outcome of bases on balls, as he currently leads the AL in walks (30) and saw his BB% climb by more than 10 percentage points. A complete profile of homers, strikeouts, and walks would fit nicely with Tampa’s extreme three true outcome lineup

Though his walks have soared in 2017, on the surface it seems Miller’s power has evaporated. He has just two homers and a career-low ISO (.114), a far cry from the .239 mark he put up last season. Like his defensive versatility, Miller’s pop is still there, if the way he is being pitched is any indication. He is seeing fewer pitches in the strike zone than the aforementioned Miguel Sano (40.7%) and his chase rate is a career-best 23.8%, way down from the 32.4% figure he put up last season while transforming into a power bat. His contact, however, has been worse (average exit velocity down from 93 MPH to 90 MPH) or more frequently nonexistent (72.2% contact rate this year down from 75.6% in 2016). Barring an incredible streak, Miller probably will not reach 30 homers this year. Because pitchers are treading carefully around his bat, though, he can still provide the Rays with offensive upside in the form of OBP.

Honorable Mention – Aaron Hicks

Image title                                                Dennis Wierzbicki-USA TODAY Sports

Walk Percent (BB%)
Plate Appearances (PAs)

Hicks, who lost a Spring Training position battle to Aaron Judge and thus began the season as the New York Yankees fourth outfielder, does not have quite enough playing time for his walk rate to be statistically significant. But at 111 plate appearances, he is oh-so-close, and his walk rate improvement from 8.3% last season to a whopping 19.8% is nothing short of astounding. The entirety of the Yankees outfield is playing well, leaving Hicks a little under the radar and is maybe not even the best “Aaron” on his team. By virtue of his .464 OBP and net-positive defensive contributions, Hicks continues to make a case for more playing time.


The One-Man Show – Wil Myers

Image titleJim Cowsert-USA TODAY Sports

Walk Percent (BB%)
Plate Appearances (PAs)

If Miguel Sano is the poster boy for a young player learning to hone plate discipline, than Wil Myers is a sort of Bizarro Miguel Sano. Although the San Diego Padres first baseman has never really ranked among league leaders in regards to his batting eye, his 10.1% BB% in 2016 was above average. Throughout the minors, never once did he see his walk rate drop into single digits. Where Sano has nearly doubled his walk rate between this season and last, Myers has seen his nearly sliced in half. 

Despite what might seem like a step backwards for the one bright spot in San Diego, Myers is actually hitting better than he has at any point in his career. He is putting up career bests in batting average (.298), OPS (.911), wOBA (.379), and wRC+ (136). His line drive percentage (25.0%) and hard contact percentage (48.0%) are both well ahead of his next-best seasons in either regard. In what appears to be an explicit strategy of his, he has for the fourth straight season cut his percentage of grounders so that his GB% is, for the first time, under 40% (39.5%). 

Whereas Myers’ resurgence last season was in part due to his ability to drive the ball to all fields, this year he is jumping on damage pitches. For his career, Myers has slashed .305/.469/.516 when ahead in the count. That’s undoubtedly great. This season, the line looks like .328/.414/.689. The OBP is down, but Myers is making his hits count with an impressive ISO of .361. There are still reasons to be wary of Myers’ aggressive approach, such as career-worst contact and chase rates (72.7% and 32.0%, respectively). Still, as a young Padres roster suffers growing pains in the NL West, Myers is the bat to watch. In a best-case scenario, he could trade walks for XBH thanks to his new attacking mentality.

The Slow-Bat Vets – Carlos Beltran & Mike Napoli

Image titleMark J. Rebilas-USA TODAY Sports

Career BB%
2016 BB%
2016 PA
2017 BB%
2017 PA
Carlos Beltran, HOU
Mike Napoli, TEX

Things are looking up in Texas. The Houston Astros are top in the AL West and have the best record in baseball. Though the Texas Rangers began the year in a funk, as of writing they have won eight straight to surpass the .500 mark (in a truly improbable run). This past offseason, both teams signed a veteran designated hitter to one-year deals in hopes of bolstering their playoff-contending rosters. Unfortunately, both additions are slumping heavily at the start of 2017. 

At 40 years of age, the Astros’ Carlos Beltran is having his worst season since 2014, and offensively the worst since his glove-first young outfielder days in Kansas City way back in 2000.  Of all the players mentioned on this list, Beltran exhibits the smallest absolute change in BB%, down just 1.8 percentage points from last season. But even that small change might be enough, as it points to an overall trend for Carlos. His walk rate has declined in each of the past three seasons (8.5% to 5.9% to 4.1%), just as his chase rate has escalated during that time (29.4% to 31.2% to 33.1%). His contact rate (76.5%) is his lowest since the data have been tracked in 2007, and his average exit velocity (85.88 MPH) is almost two notches below the Major League average. Simply put, Beltran isn’t seeing the ball like he used to.

Image title

Troy Taormina-USA TODAY Sports

Napoli’s case is similar, but the results have been far more disappointing. His wOBA is a measly .267, way below his next-worst season in 2015 (.321). The dude is hitting .181, and his normally strong walk rate has disappeared. A drop of this magnitude was entirely unexpected for Napoli, even at 35-years-old. Like Beltran, Napoli’s contact rates have worsened over the past few years, but with a career K% of 27.7% he clearly always had some swing-and-miss in his game. The clearest harbinger of decline, however, appears to be his out-of-zone contact rate, which sat at 63.1% in 2014 but has declined every year to its present value of 48.9%. With his chase rate at a career-worst 26.8%, Napoli, too, is struggling to track the ball, leading to his drastically diminished walk rate. 

It might seem counterintuitive, though, that two long-tenured veterans are growing less patient at the plate. The thought is that hitters who have been in the league longer grow more selective as they age, which allows them to maintain value even as their fast-twitch skills decline. Chris Mitchell of The Hardball Times demonstrated that there is very little evidence of players becoming more disciplined in advanced baseball age, and back in 2012 Bill Petti of FanGraphs identified that swing rates trend upwards after age 33 whereas out-of-zone contact rates decline. We observe the exact same pattern in Beltran and Napoli, and their walk rates are reminders that the end may be near for each.


The idea behind looking at rate stats at their respective stabilization points is not to project how a player will perform over the rest of the season. Take strikeouts, for instance. Last year, Giancarlo Stanton suffered through an epic slump during which he struck out 46.1% of the time in 70 PA. That did not mean he hit that poorly the rest of the way, or even that such a performance was expected down the line. However, that sample was enough to tell us that his absence of contact was more than a fluke. 

When discussing stabilization points, it is important to remember that the stats look backward. Mike Napoli might very well go back to being his patient self, and Zack Cozart may let loose a little more often in 2017. Either way, these early-season samples tell us something, whether that be a change in approach or the signs of decline. Although this series has only examined hitters to this point, next time we will turn our attention to the mound to see which pitchers have made meaningful changes in their stat lines. 

All statistics are accurate through Wednesday, May 17th.

Edited by Brian Kang, Peyten Maki.

Whom did the New York Mets acquire when they traded Carlos Beltran to the San Francisco Giants in 2011?
Created 5/18/17
  1. Noah Syndergaard
  2. Wilmer Flores
  3. Jeurys Familia
  4. Zack Wheeler

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