Mets 2026 projections: Marcus Semien

Today we kick off our annual projection series, the 14^th season we’ve done this at the site. This series accomplishes a bunch of different things, including quality content to use the first two-to-three months of the calendar year. They also give us a non-biased look at what to expect from the players in the upcoming season from the computer models. And then we augment it by including our biased takes on the players and their expected performances.

Of course, the non-biased computer numbers are based on a mid-point, a 50% expectation. Our biased numbers, on average, are much higher than that, easily an 80% expectation, if not higher. And that’s okay. It’s good to know both of those things.

One thing that I found illuminating was that after the 2025 season was over, everyone and their brother was hammering David Stearns for his pitching plan. Yet those same people were forecasting before the year started that both Sean Manaea and Kodai Senga were going to perform like a bottom SP1 or a top SP2. If those two performed for a full season like many expected – myself at the front of the line – would the plan still be criticized?

Not you Chris, we all know you were against the plan before the season started.

My sincere hope is that everyone chimes in with what they expect the players to do this year here in the individual pieces of the projection series. It’s not so much to be “right” in your forecast. Instead, it’s to get a wisdom-of-the-crowd look at expectations. If, say, 10 people chime in and the average expectation is for Manaea to throw 160 IP and he only throws 60.2 IP – that tells us something. And if those same 10 people expect an average ERA of 3.75 and in reality, his ERA is 5.64 – well, that tells us something, too.

With that as our backdrop, we’re going to simplify the process this year. We’re going to have one quantity and one quality forecast for each player. For hitters, we’ll use PA and OPS. For pitchers, we’ll use IP and ERA. My hope is that with just two simple things to project that we’ll get even more responses from the readers. And the more, the better. This is the perfect time for lurkers among the readers to become commenters.

Last year, the Mets360 hex was identified. Many, many more times than not, the first person featured in the projection series did not have a great year. After identifying the issue, Luisangel Acuna was the first player examined in 2025. The projection models saw around a .640 OPS and my forecast called for a .595 mark. Acuna ended up with a .567 OPS. The hex lives on!

Before identifying the hex, the first player profiled was one of the team’s stars. But after discovering the hex, there was no way in good conscience to do that to one of the team’s best players. So, this year’s projections will start out again with someone who I don’t see contributing all that much at the plate.

This offseason, the Mets acquired Marcus Semien to get out of the last two years of Brandon Nimmo’s contract and to improve the team’s infield defense. The club likely has hopes of Semien rebounding from a poor year at the plate in 2025, one where he posted a .669 OPS.

Proponents of the deal have pointed towards his “x” numbers, which show Semien not getting the results that his type of contact warranted. For example, his xwOBA in 2025 was .318, compared to a .295 actual wOBA a year ago. That’s a legitimate reason to hope for a better year for Semien, that his luck will turn on his batted balls.

We only have three projection systems available right now. Others will be added by FanGraphs as the year progresses. Meanwhile, we’ll just use what we have. Here’s how the computer models see Semien in 2026:

539 PA, .715 OPS – Marcel
675 PA, .714 OPS – Steamer
635 PA, .716 OPS – THE BAT

As you expect with a veteran player, the computer models all see a very similar hitter, production-wise. They differ on how much time they expect him to play, with Marcel (the simplest model of them all) being heavily influenced with Semien having just 534 PA in 2025 after four straight seasons where he reached 718 PA.

As for me, it’s not a big enough discrepancy between his “x” numbers and his actual numbers to make me a buyer of the narrative that Semien is due for a rebound in 2026. Especially given that we know he’ll be in his age-35 season in 2026. It’s hard enough for anyone that old (baseball-wise) to turn things around. And it’s even worse with guys who play second base.

The thing that gives me the most pause is wondering how much rope the Mets will give Semien if he continues to struggle at the plate. It’s very easy to see him playing every day if he’s hitting like he did in 2023. Yet will the Mets continue to trot him out there every day if he’s at the Galvis Line offensively?

Robinson Cano had 423 PA his first year with the Mets but there are two things to keep in mind here. The first is that he was the pet project of then-GM Brodie Van Wagenen. Does Semien hold that same place with Stearns? The second factor is that Cano had two stretches where he didn’t play. From 5/23 to 6/15, Cano played only one game. And he was sidelined from 8/5 to 9/3. Otherwise, he played pretty much every day.

My expectation is that there will be a leash with Semien, especially if either Acuna or Jett Williams demand playing time in the majors. Here’s my totally biased forecast for Semien this year:

595 PA, .655 OPS

So, please give hard numbers – not less than or around – for these two categories in what you expect from Semien this season. That serves two purposes, as it will aid in our “wisdom of the crowd” and it will give you bragging rights if/when your forecast turns out correct, regardless if you expect a great season from Semien or not.