Marcus Semien’s Swing Has Clicked in September

Marcus Semien
Jim Cowsert-USA TODAY Sports

I remember the first time I heard Marcus Semien talk about hitting. Coming off a fantastic season with the Blue Jays, he was a finalist for the AL MVP award along with teammate Vladimir Guerrero Jr. and the eventual winner, Shohei Ohtani. Not many likely paid him much attention during his interviews on MLB Network’s award show; as you would expect, everybody was patiently waiting for Ohtani to talk about his historic season on a national stage. But in every Semien soundbite during his interview with Greg Amsinger, there was a fascinating tidbit about hitting and progressing through a season. Since then, I have looked at his at-bats differently.

That’s what made watching Semien in the first two months of the season mind-boggling. He was one of the worst hitters in baseball, with a 55 wRC+, and couldn’t keep the ball off the ground. I’m a big fan and supporter of his swing, but that performance had me doubting what his future would be. But the Rangers’ second baseman got hot in the early summer, posting a 137 wRC+ over June and July, and after an average August, his September has been one of the best months of his career, with a .337/.388/.589 line and a 177 wRC+.

Through all that, Semien’s hard-hit rate stayed consistent, including his awful start and two great months in June and July, but since hard-hit rate is strictly a measurement of exit velocity, that isn’t all that surprising. What is a shocker is how he’s nearly doubled that same rate month over month.

Hard Hit Rate By Month
Month Hard%
Mar/Apr 23.9%
May 27.0%
Jun 25.3%
Jul 30.3%
Aug 24.5%
Sept/Oct 45.8%

On the year, Semien ranks 95th in all of baseball in hard-hit rate, but in September, he has ascended to 15th among all qualified hitters. That type of jump is sticky and often indicative of a concrete swing adjustment. In other words, you don’t luck yourself into hitting rockets for this long. So let’s find out what that change was.

I’ll start by showing the change in his stance from May to July to September:

Here’s the thing about stances: By no means are they the most important part of the swing. For some hitters, they don’t matter too much at all. But there is no such thing as an absolute. Semien’s setup helps him in get in a better position to balance his hand load with his leg kick. Any disconnect between the two can lead to the ground ball-heavy stretches that he deals with occasionally.

You can compare what Semien is doing to when pitchers like Max Scherzer and Walker Buehler move their hands overhead in their windup. For them, it’s necessary to feel how their upper body is connected to their lower body through each phase of the throwing motion. The same goes for Semien: He needs this feel to be consistent.

You can see how important that connection is for Semien by looking at his positioning at peak leg lift in each of the those same three swings:

The leg lift itself is consistent through each of these three screenshots, but the angle of his bat and hand placement has gone from high and tight to closer to neutral. The knob of the bat was pointing toward the umpire’s shoulder in May, but in September it’s pointing more toward the umpire’s knee, resulting in his hands working their way further and further from his body. That may seem like random noise, but I recommend you stand up and get into a leg lift like Semien does. For any given person, there is an optimal placement of their hands in front of their body to allow for a smooth transition into the bat comb and loading of the barrel. (The bat comb is the motion of a hitter’s barrel moving over/near their head as they stride forward; it can be a big or small motion depending on the hitter.) It’s all about comfort in every movement, from bat comb to hand placement in the stance. For you, that may mean hands low near your hips; for me, it may mean high near my shoulders.

Semien wasn’t loose in his load in May because of this disconnect — it looked segmented rather than taking place in one fluid motion. If you look at how far the ball had already traveled out of Reid Detmers’ hand, you’ll notice Semien wasn’t giving himself much time to make a swing decision, relative to the swings in July and September. And rushing your foot down without ideal balance means you won’t get the ball in the air with consistency.

Even when you compare July to September, you can see Semien is settled in his leg lift as JP Sears is releasing the ball, giving himself plenty of time to load and make a swing decision. I’m a firm believer in the idea that a hitter with this type of leg kick should focus on getting their foot up in time rather than down. Any athlete who is reliant on balance shouldn’t rush to make any movement; it needs to be fluid. Semien uses his landing leg as a wall to decelerate his body in preparation of swinging or not. To put that into better context, this deceleration is the moment when a hitter pauses right before they make a decision to swing.

A controlled, soft landing helps a hitter avoid favoring one part of the body too much. The best decelerators often have the highest hit tools, too. And I don’t mean a David Fletcher-type hit tool, but a Mookie Betts-type hit tool. If you can absorb energy with your landing leg, you’re in a great position to make a good swing on pitches in every part of the strike zone. It’s tough to absorb that energy properly if you’re rushing to get down because you took too long to get up.

A lot of the time it’s difficult making an exact distinction on what changed in a swing since there are so many parts to it. But in this case, the setup and stance have Semien in a better position to let his swing and body do the work. When you’re as gifted a hitter as he is, sometimes all that’s required is relaxing your body and letting your swing work freely through the zone with no hiccups or hitches.

Esteban is a contributing writer at FanGraphs. You can also find his work at Pinstripe Alley if you so dare to read about the Yankees. Find him on Twitter @esteerivera42 for endless talk about swing mechanics.

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2 months ago

Really cool stuff, Esteban! I really appreciate your clear explanations of these mechanical nuances. One tiny thing, though: are the hard-hit rates by month in the table all correct? You write that Semien has nearly doubled his hard-hit rate month-over-month, and I also infer that his September/October rate must be his highest of the season, but the table shows a hard-hit rate of 21% in August and 30.3% in September/October, but also 30.5% back in May. Would you mind clarifying? Thanks!

2 months ago
Reply to  Esteban Rivera

Thank you! And wow, yeah, that is a massive jump this month. This may be a dumb question, but is there a rule of thumb as far as judging whether an increase in hard-hit rate is likely to be sticky, and not just normal in-season variance/noise? Just curious. Thanks again!