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  • Chris Clegg

Hitters With Large BA and xBA Differentials

Stock Photo: San Diego Tribune

With the rise of analytics, Statcast data, and sabermetrics in baseball, we are seeing a change in the way MLB teams play, as well as fantasy baseball players. With Statcast data more accessible than ever, fantasy players can get a leg up on the competition by looking at players' advanced profiles. Baseball Savant has become one of my favorite sites to turn to when studying a player to help look deeper into a hitter or pitcher. Expected player outcomes remove the defense and ballpark factors from the equation to try and show a player's true skill at the moment of batted ball contact. This article is a deep dive into players who both under and over-performed their batting average in 2019.

Expected Batting Average or often referred to as xBA, is a Statcast metric that measures the chances a batted ball will become a hit. Each time a player records a batted ball, it is assigned an xBA based on how often a comparable hit ball becomes a hit. This is based on exit velocity, launch angle, and in some cases sprint speed.

For example, a player hits a line drive in the right and center field gap and that batted ball is given an xBA of .800. This is because balls hit in that area of the field with a similar exit velocity and launch angle have become a hit eight out of 10 times.

Expected batting average is useful because it can be more suggestive of a player's true skill rather than their actual batting average. Knowing the expected batting average of a player can help you in your preparation for your fantasy drafts, because an xBA may be more indicative of what a certain player might actually produce the following season in the batting average department. While there are some exceptions of players who vastly over or under-perform their xBA from year to year, the stat is helpful when predicting what a player might do. Now that you know a little more about xBA, let's look at some players who over and under-performed last season.


Fernando Tatis Jr., SD (NFBC ADP 16)

Tatis busted onto the scene during his rookie campaign last season hitting .317 with 22 home runs and 16 steals in just 372 plate appearances before his season ended in August due to back problems. Tatis had the highest BABIP of any player in the league with at least 350 plate appearances at .410. Tatis has elite sprint speed which helps support the high BABIP, but digging a little deeper, it looks like it will be hard for Tatis to sustain these numbers. He had the highest differential in batting average and expected batting average at .058, leaving the expected number at .259. This stat says there should be some major regression in the batting average department. Tatis will likely always outperform his xBA and have a high BABIP due to his high sprint speed. While I do believe that Tatis will have MVP type seasons in the future, we should temper our batting average expectations on him for the 2020 season. I expect him to hit closer to his career minor league average of .280. The rest of the Statcast data looks good, as you can see in the picture above. Tatis has the upside to push 30/30, making him a very valuable asset to your fantasy team. Knowing the upside helps justify the ADP some, but I personally will not be taking Tatis in redraft leagues at the current ADP.

Nolan Arenado, COL (NFBC ADP 14)

Arenado has been one of the most steady hitters in baseball over the past five seasons. Since 2015, he has averaged right at 40 home runs with a .300 average per season. Those numbers provide a huge boost to your fantasy team. Seeing that Arenado was ranked third in his BA and xBA differential could be concerning to some. Digging a little deeper it is clear that Arenado is no stranger to having a low xBA while constantly outproducing it. Coors Field is a big factor, being the most hitter-friendly park in baseball. RotoGrinders park factors show each stadium and the effects it has on hitters for different statistics. With 1.0 being the average, Coors Field rates out in batting average at 1.2 for right-handed hitters and 1.17 for left-handed hitters. It comes as no shock that Arenado hit .351 at home and .277 on the road. Almost every Rockies hitter has splits that are this extreme. As long as Arenado stays in Colorado and is not traded, there is not much reason to worry that batting average regression is coming. At his ADP, I love getting Arenado on my team and getting a solid head start in the four categories he is a major contributor in.

Kris Bryant, CHC (NFBC ADP 57)

Kris Bryant is a player who after the 2016 season showed he was more than capable of being one of the best players in baseball. Injuries have plagued Bryant in recent years and his shoulder issues zapped much of his power in 2018. Coming into last season healthy, Bryant still under-performed in a general sense hitting .282 with 31 HR/108 R/77 RBI. Coming into 2020, Bryant's ADP has dropped significantly to 57 overall in NFBC. In 2019, Bryant vastly over-performed his xBA by .036 leaving him with sixth-highest differential. His .246 xBA does not provide hope to owners who are looking for a rebound season, but for his career, Bryant has a .257 xBA, while having a career .284 average. 2020 is a big season for Bryant, will he trend closer to his elite 2016 form or will he stay closer to last year's production? Time will tell. For now, I think Bryant can provide great value to owners who take him near his ADP.


Marcell Ozuna, ATL (NFBC ADP 99)

I love Marcell Ozuna coming into this season. Ozuna comes in as the largest under-performer of his xBA according to Baseball Savant, at -.047. While hitting an underwhelming .241 last season, the expected numbers peg him at .288. Ozuna signed a one year, "prove it" type deal with Atlanta this offseason. He should hit cleanup behind some really good hitters providing a lot of RBI opportunities. The Statcast data looks really good as you can see in the chart. Ozuna was 90th percentile or better in exit velocity, hard-hit percent, xwOBA, and xSLG. His expected batting average was 86th percentile. The 2017 season remains an outlier for Ozuna when he hit .312 with 37 home runs with the Marlins, but this could be the year Ozuna gets close to those numbers again. I expect him to hit .280+ with 30+ home runs and a lot of counting stats in a good Atlanta lineup. I am taking Ozuna in almost all drafts, as I think he will provide great value for owners who take him.

Justin Smoak, MIL (NFBC ADP 481)

Smoak was a relatively below-average hitter until his breakout in 2017 where he hit 38 home runs with a .270 batting average in Toronto. He has been good but not great each of the last two seasons with 25 and 22 home runs and a .242 and .208 average respectively. Now, Smoak finds himself in Milwaukee as the projected starter at first base. Last season, Smoak had the second-largest negative differential between his batting average and expected batting average at -.042. Smoak also ranked first in under-performing his slugging percentage. While I am concerned he will split time with Ryan Braun at first base, I still think Smoak can provide great value for Milwaukee and fantasy owners. He is essentially free in all drafts and is worth a flier in deep leagues as I expect him to hit in the .240-.250 range with 25+ home runs.

Danny Jansen, TOR (NFBC ADP 273)

Jansen was many analyst favorite breakout at the catcher position prior to the 2019 season. He underwhelmed by hitting .207 in 384 plate appearances. Jansen finds himself with the third most under-performed batting average according to Baseball Savant with a -.040 differential. With this being Jansen's second full season in the majors, I expect him to take a huge step forward this year. In 1505 career minor league plate appearance, Jansen produced a .269 batting average. With an xBA of .247 last season in his first full season of major league pitching, I think he will take a big step forward this year. With the wasteland that the catcher position is, if Jansen can hit close to .250 with around 15 home runs, he will provide great value for you, especially considering his ADP and the fact he is the 19th catcher coming off the board. If I miss on Realmuto, Sanchez, and Grandal early, Jansen is a guy who I will be looking to take later in drafts.