Marcus Semien Is a Shortstop Now

At a lazy spring pre-game meeting with Bob Melvin a few weeks back, he mentioned off-hand that Marcus Semien wasn’t going to play every day. For half a second, it seemed we had a bit of a scoop on our hands, an emerging platoon at shortstop for the Athletics. But then, that was worth a confirmation — “You just mean he’s an Athletic, right?”

Yeah, Melvin said, “We don’t play anyone everyday. But when he’s playing, he’s playing short.” Less of a scoop, but still interesting, was this confirmation of what Billy Beane said during the winter meetings about Semien’s new-ish position.

Here’s a player that had played all over the diamond in Chicago, coming to a new team to take over one position as a starter. That hasn’t happened much before. In fact, only four players since 2002 have left one team as a utility man and arrived on their new team as a shortstop — Adeiny Hechavarria, Craig Counsell, Jed Lowrie, and Julio Lugo.

The manager and the player were upbeat about what the position switch would mean for his defense. As the latter three names show, it isn’t a move that’s usually done with defense standouts, but there might be something about focusing on one position that helps.

Anecdotally, it makes sense that settling into one spot on the infield would be good for the glove. “When you’re playing third, obviously it’s a different throw, and when you’re playing second it’s a considerably different throw. So for a guy that’s as versatile as he is, being young, it’s tough to find that consistent arm slot,” Melvin said of his young shortstop.

For Semien, we can see this easily in just a few highlights of his defensive plays. Up first is a throw from second base, and then below that is a throw from third.

Semien shrugs the arm angle thing off a bit if you ask him. “There have been all kinds of different errors I’ve made, different plays I’ve made,” he said of playing different positions.

But not necessarily buying that the positions had an effect on his arm slots doesn’t mean that Semien doesn’t think that it’s nice to settle down. “It’s been fun just focusing on my favorite position. Same reps every day, same throws every day, maybe that has a little something to do with it,” he said of improving his glove and taking over short.

His manager confirmed that there was specifically work going on with Semien and Mike Gallego and finding a consistent arm slot, but also put that work in a larger context for the player. “Everyone is going to have strengths and weaknesses and maybe in the past that’s been one of his weaknesses,” Melvin said. “Our early work starts at eight and he’s out there almost every day.” The manager felt the work was having an effect and that Semien was improving his arm slot and showing good defense in camp, too.

Placed within the larger context of young utility-men turned shortstops, it’s believable that the position switch will help. The defensive metrics in one-year samples aren’t something to depend on, we can still use them to point out a couple trends in the sample of comparable players to Semien.

Since 2002, seven players have spent a year playing three infield positions or more (minimum three games) and then switched full-time to shortstop the next year. Hechavarria, Lowrie, Counsell, Lugo, Cliff Pennington, Marco Scutaro, and Brendan Ryan. Five of the seven improved their shortstop UZR/150 when they moved to shortstop. Brendan Ryan was the sixth, and he just went from super duper awesome to awesome. Only Marco Scutaro, who was scratch in 56 games at short in 2008 and then a -17 shortstop the next year, was really exposed with a full year at short.

If we’re going to look for a comp for Semien in this list, perhaps Julio Lugo is the place to look. The question with players like Ryan, Hechevarria, and Pennington wasn’t if their gloves would play at short — the question was only if they could hit enough to start every day. And Semien seems a little more athletic than Lowrie and Scutaro.

The best comp might be Julio Lugo, who did well his first year at short, but then had his detractors thereafter. Interestingly, his infield coach Luis Alicea had this to say about Lugo’s errors in 2009: “All of his errors have pretty much been throwing. On the throws, it’s all been with his feet. When he sets his feet, he makes good throws.”

Marcus Semien probably has the range to play short. He’s projected to be about 5% better than league average with the bat, so his bat will be fine there. He may not play short forever, and throws may have something to do with that later, but our samples are so short, it’s worth finding out if sticking to one position and one arm slot will fix some of those issues.

In the end, it doesn’t matter what we think, and the past comps are not so plentiful that we can say anything definitive. The team is playing him at shortstop, and the player is excited for the chance. “Playing short is what I want to do,” said Marcus Semien.

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With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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He’s projected to be about 5% better than league average with the bat, so his bat will be fine there.

Those projections are based on radical improvement in his strikeout rate, putting him much closer to his 17.2% minor league total than his 28.2% major league K%. The problem is that there’s a real reason for his K% being so much higher in the majors. Despite his walk rate, Semien doesn’t appear to have much ability to differentiate between balls and strikes. He walked frequently in the minor leagues because of his passivity and the lower strike percentage for minor league pitchers.

Through an admittedly small 326 PA sample, Semien’s overall swing percentage of 43.1% put him in the bottom quarter of the league. A low swing percentage is great if you’re taking pitches you shouldn’t be swinging at anyway, the problem is that Marcus ranked toward the bottom of the league in Z-Swing% while being higher than average in O-Swing%. Perhaps it is precisely that struggle to identify strikes from balls that is behind Semien’s passivity, but whatever the cause, it has compounded his issues at the plate. Thus far he has put the first pitch in play on just 5.2% of his plate appearances, while more often than not he has begun with an 0-1 count. Meanwhile Semien’s Contact% (54th of 56) and Z-Contact% (51st of 56) are both among the very worst for shortstops, while his IFFB% is slightly worse than the average (30th of 56) as well.

To be clear, I am not writing Semien off. I personally was not impressed with what I saw of him in person in the minor leagues, but I do expect his O-Swing% and Z-Swing% figures to improve somewhat. Unfortunately there’s so much wrong that even modest improvement leaves him as a below average hitter despite what would appear to be promising minor league totals. For him to reach the level you and the projection systems assume, his improvement will need to be fairly extreme.


Very interesting – thanks for posting.

Eno Sarris
Eno Sarris

There is a ton of room for him to disappoint with the bat and be okay. The average AL shortstop is like 14% worse than league average! Point was only to place him in context of his peers, and the decisions to play them at short full time were also using projections at the time.

Rational Fan
Rational Fan

You weren’t impressed by him in the minors? Didn’t he win the AA player of the year? He had a 906 OPS, with 15 HR’s and 20 steals in only 105 games.

Semien has walked a ton in the minors; it goes much further than he takes a lot of pitches. He struggled with pitches low and out of the zone last year; it was a clear hole in his game. That said, I think discrediting his minor league walk rate as merely minor leaguers throwing more balls accompanied by his patience is far too simplistic. If it was that easy to walk 80 times in a season, while only striking out 67, then every minor leaguer would be showing that level of patience at the plate.