Statcast Standouts: xBA Underperformers

Statcast’s use of expected stats can be helpful in evaluating a player’s performance. Expected Batting Average (xBA) is a statcast metric that measures the probability that a batted ball will become a hit. Every batted ball is assigned an xBA on comparable hit balls in exit velocity, launch angle, and sprint speed on topped or weakly hit balls.

Each batted ball is assigned that xBA based on the factors mentioned in the previous paragraph. Using the expected outcomes of each player’s batted ball helps form their season-long xBA. Strikeout totals are factored into the equation, resulting in a player’s overall Expected Batting Average.

A player’s xBA for the season is calculated by taking the sum of all xBA from individual batted ball events. The sum is then divided by all batted ball events. After that, strikeouts are factored in, which results in a season-long Expected Batting Average.

Expected Batting Average can help give us a better picture of a player’s true skill level than batting average itself. xBA removes defense from the equation, meaning the results are based more on the hitter’s skill level. Because hitters can influence exit velocity and launch angle to an extent, xBA is useful. Once the ball leaves the bat, a hitter cannot control the outcome.

Many were quick to point out early in the season that the unknowns with the baseballs led to some wonky expected stats. Throughout the season, numbers have stabilized, though. League-wide batting average sits at .242, while xBA is .255.

Statcast Expected Batting Average Underperformers

Using statcast data and expected stats, we can pinpoint some hitters who could be in for better seasons in the second half. Expected stats are by no means perfect, but we can look at players who are severely underperforming their xBA’s. I have compiled a list of top-ten underperformers of expected batting average and will discuss some interesting underperformers below.

Corey Seager, SS, Texas Rangers

It has been an interesting season this year for Corey Seager, who has 19 home runs and a .245 batting average. Seager has been one of the more steady hitters throughout his career with a .291 career batting average which includes a .307 and .306 average the last two seasons. He currently has a career-best strikeout rate of 16 percent and a walk rate of nine percent. Things look really good under the hood for Seagert despite a .245 batting average.

Seager currently has a .304 expected batting average according to statcast and is already seeing his actual results trend closer to his expected average. Seager has a .382 batting average in nine games in July with four home runs. His expected slugging percentage is also currently .592, so you can also expect that to come up. You can see the rolling chart of Seager’s batting average below and see he is trending in the right direction.

Based on what we have seen Seager do throughout his career, you can expect a batting average close to .300 rest of the season. He is also on pace to blast his career-high home runs. It is a bit surprising that Seager has never hit more than 26 home runs in his career, but 30 is a good mark to beat by the end of 2022.

Byron Buxton, OF, Minnesota Twins

It has been a bumpy season for Byron Buxton, who checks in with a .215/.295/.550 slash line. The slugging percentage is impressive, and he currently has 23 home runs backed by some of the best barrel and hard-hit rates in the league. But why is his batting average so low?

It starts with a .208 BABIP. Buxton’s BABIP is lower due to the number of home runs he has hit this season, but it is still low for a player with his sprint speed. Another reason for the lower average is due to a drop in line drive rate this season. Buxton has been hitting more fly balls, therefore getting to more home runs, but he is sacrificing batting average in the process.

Statcast’s expected stats paint a better picture and give Buxton an expected average of .258. Buxton has had some unlucky breaks combined with the increase in home runs leading to the batting average dip. But, you can expect his .208 BABIP to come up in the second half, pushing Buxton’s batting average up significantly.

Yordan Alvarez, DH, Houston Astros

Yordan Alvarez may have recently arrived on the Injured List with a hand injury, but is worth talking about here. It has been a stellar season for the 25-year-old slugger with a .306/.405/.653 slash with 26 home runs. Yordan ranks first among all hitters in average exit velocity, hard-hit rate, xBA, xwOBA, and xSLG. His season has been excellent.

The crazy thing is that statcast says he is underperforming his expected batting average by .044. His expected batting average at .350 is quite impressive and a testament to how hard he is hitting the ball with excellent contact skills.

I would not expect Yordan to hit .350 rest of the season. You can expect consistent performance when he returns from injury after the All-Star break. Alvarez is a stud hitter.

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