Statcast Hitter Studs and Duds: Using wOBA + xwOBA to Predict Second-Half Regression

It's time for the official second half of the 2023 Major League Baseball regular season as the fun is just beginning! Be sure to also check out all of our Statcast analysis for fantasy baseball, including the weekly series by Connelly Doan about Statcast Pitcher Studs and Duds.

As we inch toward important dates on the MLB calendar, namely the Aug. 1 trade deadline, division races and playoff position jockeying will be at the forefront of the attention from here on out. That being said, there are some notable players that could certainly provide their teams with a big boost with positive second-half regression. At the same time, some players have performed above their respective heads and could tail off down the stretch.

Let's dive into some notable names in fantasy baseball when it comes to likely regression on both sides of the coin. Remember, regression is never a sure thing but we can combine the wOBA and xwOBA to get a solid look at the best second-half regression candidates.

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Hitter Studs and Duds for Fantasy Baseball

Vladimir Guerrero Jr., Blue Jays

wOBA - .342
xwOBA - .395

Certainly, a .342 wOBA is nothing to sneeze at but look for the 2023 MLB Home Run Derby champ to improve as the season moves along.

Guerrero's best season to date came in the 2021 campaign when he hit 48 home runs alongside a .419 wOBA across 161 games played en route to a runner-up finish in the AL MVP race. That season, his .417 xwOBA was right in line with his .419 wOBA while his .311 batting average came along with a reasonable .313 BABIP.

In fact, Guerrero's wOBA and xwOBA figures have been remarkably similar throughout his career. That is, until the first half of the 2023 campaign.

In his first four seasons, Guerrero has never had a gap larger than five points between his wOBA and xwOBA, which is wild. If that trend were to continue, that's stupendous news for the 50-41 Blue Jays who are tied for the second Wild Card spot in the American League while sitting in third place, seven games back in the AL East.

Isaac Paredes, Rays

wOBA - .378
xwOBA - .311

Isaac Paredes doesn't boast the same star power as Guerrero but he has been a very productive bat since coming over from the Tigers just prior to Opening Day last season.

As a member of the Rays, Paredes owns a .799 OPS, .348 wOBA, and 131 wRC+ across 686 trips to the plate. He's flexed plenty of muscle with 36 home runs and a .234 isolated power in that time. For context, teammate Randy Arozarena also has 36 home runs with a .803 OPS, .350 wOBA, and 133 wRC+ since the beginning of 2021. Nearly identical production between the two.

Unfortunately, it appears he's due for some regression in the coming months. Not only is the 24-year-old's xwOBA a hefty 67 points above his wOBA, but he's also lacking in other advanced metrics.

Aside from his solid strikeout and walk rates, that is not the most inspiring profile. The Rays are not a team that is relying on Paredes' production given the vast depth both in the lineup and within the pitching staff but their budding young star should see diminished production in the season's second half.

Bobby Witt Jr., Royals

wOBA: .318
xwOBA - .364

Bobby Witt Jr. has already rewarded fantasy baseball managers with a superb combination of power and speed, hitting 14 home runs, 15 doubles, five triples, and 24 stolen bases in the season's first half. There should be few complaints in the fantasy baseball community on Witt's production after entering the season as a top-five pick.

However, managers will be encouraged to know there is a strong likelihood of positive regression on the horizon. Witt boasts a sizeable 46-point separation in his wOBA and xwOBA figures, for the better. His .311 wOBA and .313 xwOBA were very much in line last season and his 99 wRC+ in his 2022 rookie season is identical to his first-half figure from his sophomore campaign.

Only this time, Witt's xwOBA is vastly superior to the .318 wOBA figure he's turned in to this point. His xwOBA ranks in the league's 87th percentile while he sits in the 93rd percentile in xBA and 89th in xSLG. He's been a Statcast leader, meaning his .318 wOBA should improve as we move along.

Jarren Duran, Red Sox

wOBA - .377
xwOBA - .328

Jarren Duran's rostership has gained traction of late as he's rostered in 58% of Yahoo leagues as he's outperformed at the plate so far this season.

Durran hasn't hit for a ton of home run power with five homers on the season but he's tied for third in all of baseball with 27 doubles while fantasy managers are pleased with his 17 stolen bases in just 251 trips to the plate.

Indeed, playing time in a crowded Red Sox outfield is an issue while his subpar production against left-handed pitching allows the Red Sox to use Rob Refsnyder and Adam Duvall in the outfield against southpaw starters. Add in his 49-point reduction in his xwOBA from his wOBA and Duran should be on the wrong side of the regression coin in the second half.

However, in this case, notable regression is far from guaranteed. Duran's Statcast data, aside from weak strikeout and walk rates, is fairly strong. He's well above the league average in several important departments, as you can see.

Obviously, Duran's value in dynasty leagues is far superior compared to redraft leagues. Those in redraft leagues may want to pump the brakes on the hype given all of the above but there's no denying Duran has been a worthwhile investment, at least until this point.

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