RADIO
In a recent article, I outlined a methodology to determine which breakout 2020 seasons from hitters would be built off of into 2021. Upon further reflection, however, I’m unconvinced that that methodology the best way to spot breakouts that will continue to improve, in large part because of its reliance on evaluating the stickiness of the breakouts.
With that in mind, I use a different approach in this article, with the following question as a starting point: how can hitters continue to improve after a breakout season? It seems like the obvious question to ask given the topic of this article, but -- to the detriment of my analysis -- it’s a question that I didn’t focus on enough in my last article.
Much of the analysis in this article is related to research done by Jeff Zimmerman here and here. Reading those articles isn’t necessary to understand this post, but both are worth reading if you’re interested in more research on this topic.
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Methodology
Broadly speaking, there are two ways for a hitter to improve after a breakout season. One way is to continue to improve the strength that fueled their breakout, while the other is to improve some other area of their game that didn’t fuel the original breakout. Of course, a hitter could follow up their breakout season by improving both the strength that fueled their breakout and another area of their game, but that is fairly uncommon and this distinction is generally reasonable as a result*.
Right off of the bat, it seems unlikely that most hitters commonly improve after breakout seasons by continuing to improve the strength that fueled their breakout. Regression to the mean suggests that the strength that fueled a hitter’s breakout season is likely to worsen somewhat in the following year, making two seasons of improvement in one skill unlikely. Still, it’s worth examining how hitters improve following breakout seasons in more detail.
To determine the drivers of hitter breakout seasons, I build a crude in-season xwOBA model that broke hitter production into four categories: strikeouts, walks, power, and launch angle. Those categories were measured by strikeout rate, walk rate, hard-hit rate, and sweet-spot percentage, respectively. The results of that model are summarized in the table below.
| Model r^2 | K% coefficient | BB% coefficient | Sweet-Spot% coefficient | Hard-Hit% coefficient |
| 0.875 | -0.003 | 0.005 | 0.003 | 0.002 |
Based on that model, the impact that season-to-season changes each of the four categories had in the hitter’s overall season-to-season change in xwOBA was determined. With those impacts now known (estimated) values, the two ways for hitters to improve after breakout seasons can be evaluated. But first, a breakout season has to be defined.
For this article, a breakout season is defined as a season where the hitter improves their xwOBA by at least 0.020 points from the previous season. That’s undoubtedly a flawed definition if the goal is to simply find historical breakouts; it neglects sample size, includes bounceback hitters, and focuses on expected production (xwOBA) rather than actual production (wOBA).
The crux of the issue for this article, though, is determining how a hitter can improve one season after a significant jump in production, and through that lens at least two of those flaws become features. By ignoring sample sizes the methodology is more accommodative of the 60-game 2020 season, and by focusing on xwOBA it weeds out the less skill-based breakouts who are less likely to improve in two consecutive seasons anyway. There’s an argument to be made that including bounceback candidates is less than ideal, but with an already fairly small sample, their inclusion should hopefully help provide more certainty rather than less.
With all of that in mind, I took all hitters from 2015 to 2020 who were considered breakouts by this methodology and determined which of the four categories had the biggest impact on their breakout season based on the xwOBA model. I then compared the post-breakout seasons of those hitters to each other based on their original breakout drivers.
As expected, the vast majority (slightly less than three-quarters) of breakout hitters saw their xwOBA decline in the season after their breakout year and the hitters who did improve in their post-breakout season typically improved by strengthening a different category than what originally fueled their breakout. Perhaps most importantly, though, is that the hitters who were most likely to improve in their post-breakout seasons were those who broke out with an improved walk rate as their driving category.
| Season 1 Breakout Driver | Season 1 Count | Improved Again In Season 2 | Season 1 Breakout Driver Driving Season 2 Improvement | Declined In Season 2 |
| Walk Rate | 116 | 34.48% | 12.50% | 65.52% |
| Hard-Hit % | 159 | 24.53% | 20.51% | 75.47% |
| Strikeout Rate | 95 | 29.47% | 3.57% | 70.53% |
| Sweet-Spot % | 166 | 27.71% | 21.74% | 72.29% |
| Total | 536 | 28.54% | 15.69% | 71.46% |
Hitters with walk rate-based breakout seasons were more than 25% more likely to improve in their post-breakout season than hitters with breakouts driven by the other categories, so this article will focus on 2020 breakout hitters whose breakouts were driven by improved walk rates.
Walk-Rate Based 2020 Breakouts
142 hitters qualify as having had breakout 2020 seasons based on this methodology, but only 34 were driven by walk rate improvements. Below is a list of those 34 hitters, along with their change in xwOBA between 2019 and 2020 and driving category. Players with an asterisk next to their name are elaborated on in the next section of this article.
| Player | 2019 xwOBA | 2020 xwOBA |
| Yolmer Sanchez | 0.269 | 0.393 |
| Matt Kemp | 0.205 | 0.321 |
| Magneuris Sierra | 0.213 | 0.304 |
| Aaron Hicks | 0.283 | 0.372 |
| Lorenzo Cain | 0.33 | 0.419 |
| Sandy Leon | 0.221 | 0.294 |
| Bryce Harper | 0.383 | 0.453 |
| Juan Soto | 0.408 | 0.474 |
| Francisco Cervelli | 0.283 | 0.348 |
| Harold Castro | 0.275 | 0.33 |
| Jesse Winker | 0.34 | 0.395 |
| Nicky Lopez | 0.233 | 0.287 |
| Jace Peterson | 0.294 | 0.346 |
| Jake Fraley | 0.15 | 0.199 |
| Derek Fisher | 0.295 | 0.344 |
| Clint Frazier | 0.319 | 0.368 |
| Paul Goldschmidt | 0.354 | 0.395 |
| Cam Gallagher | 0.256 | 0.297 |
| Danny Jansen* | 0.312 | 0.352 |
| Gio Urshela | 0.342 | 0.381 |
| Brad Miller* | 0.338 | 0.377 |
| Brett Gardner | 0.291 | 0.327 |
| Ronald Acuna Jr. | 0.393 | 0.425 |
| Tim Anderson | 0.325 | 0.357 |
| Kevin Kiermaier | 0.295 | 0.325 |
| Wilmer Difo | 0.264 | 0.294 |
| Jose Ramirez | 0.342 | 0.372 |
| Martin Maldonado | 0.289 | 0.318 |
| Joey Votto | 0.341 | 0.369 |
| Mike Yastrzemski | 0.341 | 0.367 |
| Miguel Rojas | 0.305 | 0.33 |
| DJ Stewart | 0.311 | 0.336 |
| Kevin Pillar | 0.299 | 0.323 |
| Chad Pinder* | 0.306 | 0.326 |
Obviously not every hitter on this list is worth elaborating on in this article. Several of the hitters are outfielders, some (like Yolmer Sanchez) had clearly unsustainable jumps in production in extremely limited playing time, and some (like Cam Gallagher) still posted poor 2020 xwOBAs and are unlikely to see much playing time in 2021. With that in mind, below are three breakouts who are relatively likely to continue improving in 2021.
2020 Breakouts To Continue Improving In 2021
Danny Jansen, Toronto Blue Jays
Jansen was a fairly popular sleeper candidate at catcher heading into last season, but investments from fantasy managers failed to pay off with Jansen batting just .183 with a similarly poor .671 OPS. Jansen managed to post a career-best .352 xwOBA that ranked eighth among qualified catchers and sat 40 points above his 2019 mark in 2020, though, qualifying him as a 2020 breakout for this article.
Encouragingly, Jansen’s 2020 breakout was primarily driven by a six-point increase in his walk rate, suggesting that he’s relatively likely to continue improving in 2021. Additionally, Jansen’s 35.5% hard-hit rate from 2020 was down from 40% in 2019, suggesting that he could enjoy some added power in 2021 as well. Combined with the fact that Jansen almost certainly suffered from some significant bad luck in 2020, Jansen’s walk-based 2020 “breakout” makes him a kind of super-breakout candidate for 2021. Fantasy managers should be bullish on Jansen’s 2021 performance as a result, and he makes for an attractive draft target at his 309 ADP.
Brad Miller, Philadelphia Phillies
I was a fan of Miller as a fantasy asset coming into last season, and it’s easy to like him again heading into 2021. Like Jansen, Miller’s “breakout” last season was obscured by some bad luck with his .377 xwOBA sitting 28 points above his wOBA. Over the past two seasons (127 games), Miller now boats a .853 OPS, and his 14.6% walk rate from last season represented a jump from 2019’s 8.8% mark.
Miller probably won’t maintain such a high walk rate in 2021 and there are questions around his playing time, but he has a very legitimate shot at an OPS above .850 once again in 2021. Fantasy managers should keep Miller on their radar as a result, and he’s a potentially worthwhile DFS option and mid-season waiver pickup if he claims consistent playing time.
Chad Pinder, Oakland A’s
Calling Pinder a walk-rate-based breakout candidate may be a bit of a stretch, but he fits the definition based on the methodology in this article and has a strong chance of improving again in 2021 after seeing his xwOBA rise 20 points between 2019 and 2020. Pinder outlined the steps he took to improve his plate discipline leading up to the 2020 season last February, and those improvements showed up in his performance. Although Pinder’s o-swing rate was up slightly from 2019 at 33.3%, his swing rate at pitches in the shadow zone was a career-low, and his swing rate at pitches in the heart of the zone was a career-high.
Pinder’s plate discipline developments are significant and appear likely to carry into 2021, making him relatively likely to sustain a z-contact rate above 90% and a hard-hit rate above 40%. Only eight qualified hitters achieved both of those marks in 2019, combining to average a .364 xwOBA. Even the worst of those hitters by xwOBA (Lorenzo Cain) posted a solid .330 xwOBA, suggesting that Pinder should be a comfortably above-average hitter in 2021.
Playing time isn’t guaranteed for Pinder this season, but he should be able to carve out at least a semi-consistent role. Fantasy managers should keep Pinder on their radars as a result, and he’s worth an investment in deeper leagues.
* To be more specific, less than one-third of the sampled breakout hitters who continued to improve in their post-breakout season had their post-breakout season improvements driven by a different factor than what drove their original breakout and saw the factor that drove their original breakout as well. Even then, those original breakout driver second season improvements were typically very small.
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