2024 Fantasy Baseball xwOBA Breakouts, Real or Mirage?

​

  • By Anthony Kates

    Last Updated on February 17, 2025 4:36 pm by André Lemos | Published: January 27, 2025

    Determining which break outs are real and which are not, is a time honored tradition across all fantasy sports. How each individual analyst and fantasy manager determines the realness of a breakout will vary in a million different ways. I’ve decided to use xwOBA to determine whether or not the forthcoming players who broke out (in some form or another) in 2024 are real or just a mirage.

    Before we dive into that though, let’s talk about two stats: wOBA and xwOBA.

    wOBA or weighted on-base average, is, according to MLB.com: “a version of on-base percentage that accounts for how a player reached base — instead of simply considering whether a player reached base. The value for each method of reaching base is determined by how much that event is worth in relation to projected runs scored (example: a double is worth more than a single).” Before wOBA, fantasy players and analysts alike had used the traditional OBP (on-base percentage) and OPS (on-base plus slugging percentage) to determine how well a player got on base and how well they produced overall when getting on base. wOBA does that while also “assigning value to each method of reaching base, in terms of its impact on scoring runs.”

    xwOBA (expected wOBA), then, expands on that, by “using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed. In the same way that each batted ball is assigned an expected batting average, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015.”

    So, why do I prefer to determine if breakout hitters are real or not using their gains in xwOBA? I use it because it is more indicative of a player’s skill than wOBA because it takes defense out of the equation. Once a batter hits the ball, whatever happens after that is out of their control, so a more accurate reading of a hitter’s ability comes from the aspects that they can control – namely launch angle, exit velocity and bat speed.

    So let’s take a look at the table below, where I have a group of seven players who saw a significant gain in xwOBA (19 points or more) from 2023 to 2024 and determine whether or not the gains are real or not.

    WordPress Data Table Plugin

    Joey Bart – C – Pittsburgh – 2024 stats: 282 PA, 38-13-45-0-.269, 121 wRC+

    I know, I know, we are talking about a few small sample sizes here. But Bart has never had more than 291 plate appearances (PA) in a season (that was 2022) and 2024 was far and away the best season of his career. In 2020, with no PA’s above Double-A, he had 111 PA in the big leagues and posted a .248 xwOBA, in 2022 with over 300 PA at Triple-A under his belt, he posted a .296 xwOBA in the big leagues and then we see his 2023.

    2024 stands out so much not just because he set career bests in nearly every single statistical category, but because he changed as a hitter. He made better swing decisions, like a career low 26% chase rate, the first time it has been under 30% in his big league career, a career high 75.7% contact rate and 86.1% in-zone contact rate, career low 10.5% swinging-strike rate and the second lowest swing rate of his career, 43.5%. Combine those with the second best set of statcast data in his career (88.1 MPH average exit velo (avgEV), 9.4% barrel rate and 38.7% hard-hit rate) and it is no wonder that he walked more, struck out less and reached base more often, while hitting for more power than ever before.

    He missed just over a month with a broken finger, but, from the time he returned to the lineup on June 30th until the end of the year, he had the eighth highest wRC+ (114) out of all catchers with 200 or more plate appearances (and he had the second lowest PA of all catchers in the top eight over that time frame; only Willson Contreras had less due to injury).

    I’m not saying he will be a top 10 catcher in 2025. He will spend plenty of time behind the plate for the Pirates, though he will share time with Endy Rodriguez, catcher of the future, taking a seat when Rodriguez is not playing first base. Projections are treating Bart rather harshly, projecting the same or less power even though they predict him to get at least 100 more plate appearances than he did in 2024. I predict he will be a serviceable number two catcher in two catcher leagues and will be able to start in one catcher leagues for stretches at a time.

    Real or Mirage? Real. Buying as a C2 in two catchers leagues and streaming him in one-catcher leagues if my starter gets hurt/falters.


    Want to get access to the rest of this article? You’ll need to have an MLB FantasyPass membership. Click here to learn more and sign up!
    Premium Access Required

    Click here to join us on Discord!
    Follow us on X by clicking here
    Follow us on Bluesky by clicking here
    Come join us at SportsEthos by filling out an application by clicking here
    Follow Anthony on X at @akfantasybb
    Follow Anthony on Bluesky at @akfantasybb.bsky.social

    January 27, 2025, 10:00 am