Why Marcus Semien's sterling season is headed for a slowdown

·MLB Writer
·4 min read
NEW YORK, NEW YORK - MAY 27: (NEW YORK DAILIES OUT)  Marcus Semien #10 of the Toronto Blue Jays in action against the New York Yankees at Yankee Stadium on May 27, 2021 in New York City. The Blue Jays defeated the Yankees 2-0. (Photo by Jim McIsaac/Getty Images)
Toronto Blue Jays second baseman Marcus Semien has been on fire to start the 2021 season but there's reason to suggest he can't keep up his current pace. (Jim McIsaac/Getty Images)

Thanks to his league-best offensive production, Vladimir Guerrero Jr. has dominated the discourse surrounding the 2021 Toronto Blue Jays — and rightfully so.

There’s only so much discussion a fourth-place team with a 31-28 record is going to drive, and it figures that it would centre around one of the game’s most exciting stars and a legitimate MVP candidate — especially in the absence of the club’s $150-million man, George Springer.

Even so, the long shadow Vladdy has cast seems to be enveloping the team’s other major offseason acquisition, Marcus Semien. Semien enters Thursday’s action with a .290/.358/.517 line and 2.7 WAR — good for the seventh-best mark in the majors among position players. If Guerrero Jr. hadn’t taken off there would be reason to bang the drum for the second baseman to get some MVP consideration himself.

It’s clear the Blue Jays would be in a much worse situation without Semien, who appears to be having a very similar season to his masterful 2019, when he hit .285/.369/.522 and finished with 7.6 WAR. Unfortunately for the club, despite Semien’s hot start, he doesn’t seem likely to continue his torrid pace.

Using Semien’s outstanding 2019 as a comparison point, it’s clear his underlying numbers simply aren’t as strong this year, starting with his walk and strikeout rates.

Marcus Semien's walk rate vs. strikeout rate 2019-2021.
Marcus Semien's walk rate vs. strikeout rate 2019-2021.

There’s a lot more swing-and-miss in Semien’s game than there was in his career season, and he’s not compensating by drawing more walks. He’s not hitting for a tonne more power either, although his ISO of .227 is similar to the excellent .237 he posted in 2019. The reason Semien’s production has been so strong is the accumulation of hits. His 69 hits ranks ninth league-wide, and his BABIP of .350 is unlike anything he’s done since his 21-game rookie cameo in 2013.

As a premise, the idea that Semien is having a great year because he’s racking up knocks is intuitive. It certainly doesn’t sound like a red flag. However, there's a massive discrepancy between the second baseman’s quality of contact and the results that have followed. That shows up in his expected stats, which gauge what level of production the way he hits the ball (combined with his walks and strikeouts) warrants.

Marcus Semien's expected stats.
Marcus Semien's expected stats.

The 50-point difference between his batting average and expected batting average is the ninth-biggest in the majors, similarly the gap between his slugging and expected slugging ranks 16th, and his wOBA-xwOBA difference is 11th.

Few players are overperforming their batted balls like Semien, which makes sense when you dig a little deeper on how he’s getting some of his hits. For instance, the second baseman is hitting .339 on ground balls — way above the league average of .228. Even his home runs, which should theoretically be his most unimpeachable hits, have consistently been wall scrapers. The 13 homers he’s hit looked like this…

Marcus Semien's spray chart.
Marcus Semien's spray chart.

… and his average home run distance of 385 ranks 112th among 120th qualified hitters who’ve gone deep at least once. That makes it seem unlikely his power production is going to hold up.

Just because that information could be used to contextualize what Semien has done so far and recalibrate future expectations down a touch, it doesn’t mean it’s all bad news for the Blue Jays. Even if Semien’s productional was more in line with his xAVG and xSLG, he’d still be having an above-average season with the bat. He’s also playing elite defence at second base and providing value on the bases. Semien’s even found his groove swiping bags, with eight steals already. By the end of the year he could blow away his previous career high of 14.

Semien’s all-around contribution to this team shouldn’t be taken lightly, even if his offence seems likely to regress. Barring a total collapse he’ll provide excellent value on the $18 million contract the Blue Jays signed him to — plus stability in the lineup and at second base. It just appears that his 2019 form is more elusive than his current numbers suggest.

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