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MLB: All Star-Home Run Derby
Though he didn’t get in the game on Tuesday, there’s no doubt Luis Robert Jr. belonged in Seattle this week.
Steven Bisig-USA TODAY Sports

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The small adjustment behind Luis Robert Jr.’s monster season

Going from a wide-open stance to a relatively closed one — plus a little relaxation — is paying dividends

There’s something different about Luis Robert Jr.

Not that you needed me to tell you. The stat line speaks for itself. His 26 homers are already a career high, and second in the AL. After a relatively pedestrian 110 OPS+ last year, he’s cut his ground ball rate by seven points, putting it in the air more than ever, and even though he’s striking out at his highest clip since his rookie year, it hasn’t mattered. Both versions of WAR have him as one of the five to seven best players in the game over the season’s first half.

What is that difference? It’s a little simpler than you might think.

Let’s work backwards. First, a few charts for you. Measured by wOBA — which you can think of as a more accurate combination of OBP and SLG than OPS — he’s gone back to mashing fastballs (.417) and breaking balls (.340) at close the same level that he was when he played at an MVP-caliber level in his abbreviated 2021 season.

Luis Robert Jr.’s wOBA by season by pitch group.
Baseball Savant

One doesn’t have to worry much about the drop in production against off-speed pitches, since they comprise fewer than 10% of the pitches he’s seen this year.

But let’s go a little farther. When you break things down on a pitch-by-pitch level, it starts to become a little clearer where his massive burst of power is coming from.

LRJ’s wOBA by season and pitch type.
Baseball Savant

We’ve seen Robert hit curveballs like this before, but he’s never been more productive against four-seam fastballs than he has this year. It’s not just a personal best, either. While 246 hitters have seen at least 250 four-seamers this season, not a single one of them tops Robert’s .555 wOBA on those pitches.

It’s absolutely not a fluke, either: Robert’s .527 expected wOBA on four-seamers is also the highest in the league. Given that four-seamers are the most commonly-thrown pitch in the game, that’s going to lead to a very, very good bottom line, statistically speaking.

So, Robert is mashing four-seamers better than he ever has. Let’s go another step further and find out what he’s doing against them now that he hasn’t done in the past.

Let’s look at location charts. Here’s what Robert’s Isolated Power — you can think of that as a better version of slugging percentage — against four-seamers looked like based on location during his white-hot 2021 season.

LRJ’s power production against four-seamers in 2021.

That’s pretty dang good! He had some holes in swing, mostly against pitches on the outer edge of the plate, but that kind of deep red is impossible to complain about. But as we know, things took a pretty big turn for the worse during his even more injury-plagued 2022 season.

LRJ’s power production against four-seamers in 2022.

You still couldn’t get away with throwing him a heater right down the middle (as one would hope), and he was still pretty good at turning on pitches inside. But those holes in his swing got a lot bigger, in a way that can’t be completely chalked up to injury.

Again, as we’re seeing, it’s been a totally different story this year.

LRJ’s power production against four-seamers in 2023.

It’s nothing short of a pitcher’s nightmare: There’s not a single place in the strike zone you can throw Robert a fastball without getting creamed, and the number of pitchers who can survive without throwing a fastball in the zone now and then are few and far between, if they exist at all. Not only is Robert’s .661 ISO on four-seamers in the zone tops in the league among the 121 hitters who have seen at least 200 such pitches, it clears second-place (Nolan Arenado, .578) by more than 80 points. Sheesh.

What happened between 2022 and 2023 to engineer such a monstrous leap in damage against fastballs? It’s an obvious change, but one that has subtle effects with gigantic implications. Let’s get a fairly typical look at how Robert was handling outside fastballs — the persistent hole in his power production — a year ago.

That’s a pretty hittable pitch against a very hittable pitcher. A swing, to no avail.

Now, let’s move on to 2023 and take a look at another four-seamer in more or less the same location, but from a much better pitcher and with another tick or two of velocity — and a much different result.

Thanks to the camera cutaway, it’s a little difficult to see the change that I’m trying to get at, so let’s take a look at another similar pitch he took deep a little bit earlier in the season, at the tail end of his first hot streak of the season, but still before he ascended to god-tier in June.

Finally, let’s fast-forward to one more from just a few weeks ago, in the midst of a run that would have certainly netted him a Player of the Month award if his competition wasn’t probably the single greatest month of baseball ever produced by an individual player.

Where Robert once sported one of the most wide-open stances in the majors, he’s slowly closed himself off to be almost square to the pitcher when he sets up, with his front foot almost even with the other, while bringing his hands just a touch closer to his body and holding the bat slightly more upright. As you can see from the shift even from the middle photo to the one on the right, it’s gotten more pronounced as this season’s gone on.

LRJ’s narrowing batting stance.
Baseball Savant

Before even getting to the setup and swing mechanics, it’s hard not to notice just how much more relaxed he looks in his stance than he did in 2022, a relaxation that’s seemingly increased along with his comfort level at the plate in 2023. That’s the first step in going from being late on a Drew Hutchison fastball to crushing them in the same spot against even faster pitches. Whether it’s at the plate or in the field, the same principle applies: When you tense your muscles in preparation to make an athletic movement, you first have to un-tense them before they can start moving in the direction you want them to. It’s why you almost never see a fielder standing completely still as a pitcher makes their delivery, and in the batter’s box, that extra fraction of a second can be the difference between being late on a pitch and hitting it on the barrel out in front of the plate.

The same core principle can be found in the closing off Robert’s batting stance: Simplifying movements and shaving off those precious milliseconds that were preventing him from meeting the ball in front of the plate and taking advantage of his raw strength and bat speed. This is where the changes are subtle and the effects are enormous. Take that swing against Hutchison and freeze it at the exact moment that his front heel digs into the ground.

Notice that even though his foot is down and he’s already started to fire his hands towards the ball, Robert has yet to engage his lower half and begin rotating his hips and core. The result is that even though the pitch was barely 93 mph, he’s late on it and can only foul it off. More broadly, even when he was able to put those pitches in play last year, he frequently wasn’t getting it out in front quickly enough to pull the ball in the air and make use of his prodigious power.

Here’s another example:

Against that Nathan Eovaldi fastball, Robert still managed to make good contact and hit the ball hard in the air, but because that contact didn’t happen until the ball was already crossing the plate, the result was that it didn’t have the elevation or the exit velocity to avoid being caught.

Having seen all that, let’s freeze-frame another pitch and see where Robert’s body was at at the same point — the moment his front heel hits the ground hard — in that big fly swing against Luis Severino.

Not only are his hands a few inches further into his swing and bat path, you can see that his back heel is well off the ground and his front front belt buckle is clearly visible, because he’s already begun the lower half rotation that allows him to make contact with the ball in front of the plate, even though it’s near the outside corner.

Getting too granular on any individual swing can be misleading, but when you do a side-by-side of the moment Robert’s heel hits dirt against Eovaldi and against Andrew Heaney, who doesn’t throw as hard as either Eovaldi or Luis Severino, the difference in where Robert’s body is at is even more visible. It’s stark enough that I spent way more time than usual going through both of these swings frame-by-frame just to make sure I was actually capturing them at the same point and not being misleading.

Again, individual swings and freeze-frames can be cherry-picked to make them say whatever you want them to say, but it’s a different story when there are numbers to back it up. This year, when Robert gets a fastball on the outer half of the plate, he’s pulling it literally twice as often as he did last year, and it’s not like he’s blindly selling out and making bad contact just for the sake of pulling the ball. Luis is hitting those balls in the air more than he was before (as the launch angles below indicate), while his top-tier exit velocities have remained essentially unchanged — even gaining a half a tick of average EV on those pulled pitches.

For Luis Robert Jr., more pull-side fly balls is an easy recipe for more home runs.
Baseball Savant

If you were wondering where that overall increase in fly ball rate from earlier was coming from, there’s your answer. By simplifying his setup and reducing unnecessary motion, Robert has been able to sync up his timing, hands, and legs/core in a way that’s left pitchers with absolutely nowhere to hide when they need to throw a fastball. Getting outer-half fastballs in the air to the pull side isn’t easy, but when you have as much power as he does, figuring out how to do it is a recipe for becoming one of the most dangerous hitters on the planet.

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