This story was excerpted from Anthony DiComo’s Mets Beat newsletter, written this week by Theo DeRosa. Subscribe to get it regularly in your inbox.
Back in December, MLB.com examined what Marcus Semien could bring to the Mets offensively after being acquired from the Rangers in a rare one-for-one trade for outfielder Brandon Nimmo.
So far, the veteran second baseman hasn’t contributed much. After going 0-for-4 in Sunday’s walk-off loss to the Marlins, Semien went 2-for-4 with a homer in Monday's 7-2 loss to the Reds. He's now batting .219 with a career-low .584 OPS. He’s not the only regular position player struggling on a 22-32 Mets team that's in last place in the National League East. But Semien hasn’t lived up to expectations, either.
There were already reasons for concern offensively about Semien, who followed an excellent 2023 at the plate for the Rangers with subpar seasons in 2024 and ’25. In his final year with Texas before the trade, Semien had a .669 OPS, the lowest of his career, and 15 home runs -- his fewest in a full season since 2018 with the A’s.
Semien’s declining power production and well-below-average bat speed were existing issues, but both have been magnified during his poor start to 2026. With only three homers, he’s on pace for nine, which (excepting 2020) would be his lowest total since he had six in 2014. That season, his second in the Major Leagues, he played only 64 games.
His 68.2 mph average bat speed ranks in the seventh percentile among MLB hitters this season, a tick down from his 2025 numbers (68.4 mph, eighth percentile). While there’s hardly a huge decline, Semien hasn’t shown any improvement in that department, and that isn’t likely to change at age 35. Without high-end bat speed, it’s no wonder Semien has struggled to drive the ball, with his average exit velocity down to a career-low 85.7 mph.
Things could change if Semien can keep up his 27.3% pulled air-ball rate, his highest since a career-best 28.7% clip in 2021, the year he slugged 45 homers for the Blue Jays. Ranking 25th in pulled-air rate headed into Sunday, Semien could potentially start seeing power results soon.
Based on Statcast’s quality-of-contact metrics, Semien has underperformed considerably, so some better fortune could be in his future. His .297 slugging percentage is well below his .394 expected SLG, and his .259 wOBA entering Sunday is far below his .302 expected wOBA. That latter 43-point gap puts Semien among the top 20 of hitters who have had the worst batted-ball luck this season.
Of course, the other main component of statistics like xwOBA is plate discipline, and that’s where Semien has fallen short in 2026. After striking out 17.4% of the time in 2025 and 14.6% in each of the two prior seasons, Semien’s K rate is an even 20% through Sunday’s action. His walk rate has declined to 6.2%, a career low and well below average among qualifying hitters.
Semien’s first-pitch swing rate has steadily climbed throughout his career, and in 2026, it has reached a career high of 42.7%, which ranks toward the top of MLB hitters. He’s swinging overall and chasing pitches out of the strike zone more than he ever has, trying unsuccessfully to find a recipe for success at the plate.
Graded out as a plus fielder ever since his move to second base from shortstop in 2021, Semien has taken a step back defensively with the Mets. After posting 7 outs above average and a +6 fielding run value in ’25, those numbers have fallen to -3 and -2, respectively. Among 68 qualifying second basemen, Semien is tied for 62nd in fielding run value in 2026.
Not many of his numbers with New York look promising, but there’s a reason the Mets parted with a longtime fan favorite in Nimmo to acquire Semien. Despite a pair of down years with the bat in 2024 and 2025, Semien was worth a combined 7.8 Baseball-Reference WAR -- 4.5 in ’24 and 3.3 in ’25. The year prior, he led the American League with 7.7 bWAR.
At -0.3 bWAR entering Sunday, Semien will need to orchestrate quite the turnaround to near that kind of value again. But if he can find his form defensively, improve his plate discipline and/or rediscover his power stroke (all, certainly, big “ifs”), he can still make his first year with the Mets a good one -- and perhaps become a midseason spark for a club badly in need of something to go its way.