Marcus Semien's Total Offensive Collapse Is Owed To A Frustratingly Simple Explanation

There's no way around it: The New York Mets’ bet on Marcus Semien has been a failure. Semien, a three-time All-Star, two-time Gold Glove winner, two-time Silver Slugger and third-place finisher in AL MVP voting in 2019, 2021 and 2023, arrived with high expectations, but in his age-35 season, he is having one of the worst seasons by a second baseman in franchise history.

Just a couple of seasons ago, before arriving in Queens, Semien had one of the best seasons by a second baseman in Texas Rangers history. He recorded the second-highest fWAR (6.5), behind only Ian Kinsler (7.3 in 2011), and combined something unprecedented: 100 RBIs with 122 runs scored. This year, the story has been the complete opposite. Semien has 0.0 fWAR—he was at -0.2 before a strong series against the Rays earlier this week—along with just a 77 wRC+ and a 20.8 K% rate.

His fWAR is the sixth-lowest among qualified second basemen in Mets history, and he is likely to fall even further by the end of the regular season. At this point, his batting average is the lowest of the group, and he also has the highest strikeout rate.

Edgardo Alfonzo still owns the best fWAR season (6.4) by a second baseman in franchise history since his unforgettable 2000 campaign, when the Mets faced the New York Yankees for the World Series title in the memorable Subway Series. Since then, only two second basemen have surpassed the 3.0 fWAR mark: Jeff McNeil in 2022 (5.5) and Daniel Murphy in 2013 (3.1). The Mets expected Semien to be the next name on that list, but those hopes have been broken, at least this year.

Semien’s high strikeout rates are not something that comes as a surprise in his offensive performance. However, his loss of power is only one problem within his imbalance at the plate, as his performance in most offensive areas, including his .248 BABIP, .130 ISO and 77 wRC+, is trending toward the worst of his career. The problems are not limited to his offense, either, as Semien is also costing the Mets runs on the bases, while his -2 DRS is the only negative mark of his career in qualified seasons since he began playing second base regularly for the Blue Jays in 2021.

Behind all of the inconsistencies, Semien still has the ability to produce with his swing against high velocity. Since 2022, he leads the league with 15 home runs among second basemen with at least 100 PA against fastballs that reached 96 mph or higher, and he has the fourth-highest xSLG (.425) in the rankings. That xSLG remains elite, as he produced a .455 mark in 2025 and .442 this year, ranking second and third in the majors at his position, respectively.

Instead, the major breakdowns in his swing have come when opponents throw him breaking balls. Overall, they have done so 38.3% of the time, but when they get Semien into two-strike counts, breaking balls become the opposing pitchers’ most effective weapon, with a higher usage rate (44.2%).

Semien’s swing has not been able to respond with enough impact, failing to find the formula to stop his biggest challenge at the plate.

This is the year in which opponents have thrown Semien more breaking balls than ever before in his career, and the results are already visible: his swing has fallen into the worst slump of his career. The two biggest breakdowns in his offense have come in power-related metrics. His HR% has fallen from an average around 3.0% to 0.6%, and his slugging percentage has dropped from .383 to .147.

Semien arrived in New York in exchange for Brandon Nimmo, and the Mets took on the remaining $72 million of his contract. The investment has been a failure so far. If the idea is to move on from him, New York will have limited options, starting with finding a team willing to take on the $46 million he would still be owed between 2027 and 2028. Otherwise, they will have to bet on Semien again in his age-36 season and work to make sure his adjustments can overcome what has been an undeniable display of total decline.

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