Evaluating the Consequences of the WBC: How Does the Classic Affect Players in the Regular Season?

The World Baseball Classic has become one of the most exciting events that the baseball calendar has to offer. Every three years, different countries face off in the WBC, playing for the pride of their country. It’s the only time that players get to wear a jersey that truly represents them, playing for their families and the flags they compete under.

That said, the Classic has also been controversial in recent years. Its timing cuts off many players Spring Training while increasing the risk of injury for those who play. The biggest example in the last few years has been Edwin Díaz’s season-ending injury after celebrating a Puerto Rico victory in the 2023 WBC. That injury ended any hopes that the New York Mets would be able to use their closer in a year that their bullpen desperately needed him. Beyond that, the other problem has been a question of whether players expend more effort playing for their country than for their MLB team. That has caused fans to wonder whether star players who slump in the regular season are due to their overexertion in the Classic. This year’s WBC has produced plenty of examples of exactly that problem.

Slumping Sluggers

Vladimir Guerrero Jr.

Guerrero was one of the most elite players for the Dominican Republic in the ’26 WBC. He helped lead the Dominican to an historic run that ended in the semifinals against the United States. In five games, Guerrero slugged two homers and slashed .444/.476/.944 with a 1.420 OPS. In that time, the slugger knocked in eight runs for the D.R. and was one of the hottest hitters of the Classic. That production came after Guerrero put up an All-Star campaign in 2025, leading the Toronto Blue Jays to their first World Series since 1993.

Unfortunately, that hasn’t translated to his 2026 season at all. His .730 OPS is average at best, and Guerrero has only slugged three homers through 70 games. That’s only one more than he did in just five WBC games. He’s still managed to bat .280, but Guerrero hasn’t done much to help a struggling Blue Jays club. It’s impossible to say if any of this is due to the Classic, but it certainly doesn’t help the WBC’s case.

Fernando Tatis Jr.

If you thought Guerrero was bad, Tatis has been even worse. He’s turned things around recently, slashing .284/.348/.353 with a .701 OPS. But Tatis had an historic homer drought that only came to an end three weeks ago. He’s still slugged just two homers this whole season, with one being a walk-off against the Cincinnati Reds last Wednesday. The San Diego Padres’ offense has struggled in a major way, and Tatis’ problems haven’t done much to help the situation.

Tatis’ two homers in the MLB regular season equal the amount he slugged in the WBC. In 20 at-bats, Tatis produced a .400/.538/.700 slash line with a 1.238 OPS and 11 RBIs. He launched a no-doubt grand slam against Israel that went a Statcast-projected 400 feet into the left field stands. That would be Tatis’ last homer until his drought ended against the Washington Nationals with a 451-foot bomb after 55 games.

Veteran Aces Losing Their Stuff

Aaron Nola

It hasn’t just been hitters who have struggled after their participation in the Classic. Pitchers have had their troubles all the same. Nola has posted one of the worst seasons of his career thus far. The veteran righty owns a 5.86 ERA through 70 2/3 innings. His WHIP is an abnormally high 1.47 mark, showing Nola is still able to serve as a veteran back-end option for the Philadelphia Phillies. That said, he has seemed to lose his ace status after two consecutive seasons with an ERA above 5.00.

Nola spent the WBC pitching like one of the greatest on the planet. The right-hander posted a 1.00 ERA in two starts with a 1.11 WHIP and .258 opponent batting average. He covered 9 innings for Italy in the Classic during an historic run for the country that saw them exit in the semifinals to the eventual champions: Venezuela.

Logan Webb

Similar to Nola, Webb looked like one of the greatest pitchers on Earth. The San Francisco Giants‘ ace anchored a U.S.A. rotation that returned to the WBC finals for the third consecutive time before eventually falling to Venezuela. He posted a 1.08 ERA and minuscule 0.69 WHIP and .161 opponent batting average across 8 2/3 innings. Webb also struck out 11 batters between his two starts for the US.

Since returning to MLB this season, the righty has looked downright awful. Webb started off the year with a 5.06 ERA until he was placed on the injured list with right knee bursitis. Since he was activated from the IL on May 29, Webb has looked like himself again, posting a 0.65 ERA through his last four starts (2 ER, 27.1 IP). Because of that recent success, the righty now boasts a more respectable 3.46 ERA.

Is it the Classic’s Fault?

The central question now is whether or not the WBC is responsible for these slumps. It’s impossible to say whether or not that’s the case, and no answer will ever satisfy the Classic’s naysayers. That being said, it seems like no coincidence that the stars of the 2026 WBC have performed poorly across the board in the regular season. In a group of 20 MLB hitters and 10 pitchers who also played in the Classic, the differences between their statistics are marked in the graphs below. A positive number indicates that the player performed worse in that statistical category during MLB compared to the WBC. A negative number indicates that the player performed better during the regular season compared to the Classic. The final row of each table indicates the average difference of each stat between regular season and the WBC.

Offensive Differentials

Outliers abound in each of these sets, but perhaps nowhere near as much as Oneil Cruz. His 1.928 OPS is the largest differential by a mile across the 20 batters. That incredible difference is likely due to the smaller sample size found in the Classic. With less than 20 at-bats for WBC players to make their mark, those who perform well have a hard time equalling that in the regular season, while those who struggle easily clear their WBC numbers in MLB.

Pitching Differentials

It’s a similar story on the pitching side of things, with outliers like Cristopher Sánchez and Brayan Bello present. That said, the numbers still paint a convincing picture that players, on average, play worse in the regular season than they do in the Classic. That seems more due to the smaller sample size of the international tournament than the atmosphere of the WBC. Regardless, those who dislike the risk of the WBC will certainly find this news welcome. The Classic is one of the most enjoyable events in baseball. Kids grow up watching the WBC hoping to one day represent their country on the world’s biggest stage. However the triennial tournament affects MLB, hopefully the tradition will continue.