Analyzing (But Also Enjoying) Jorge Mateo’s Hot Start

Jorge Mateo
Tommy Gilligan-USA TODAY Sports

Well, shoot. After grounding out to shortstop in the second inning of Wednesday night’s game against the Nationals, Jorge Mateo was removed due to hip discomfort. The Baltimore shortstop is officially day-to-day, and Rotowire reports that he seems to have avoided a serious injury, but the timing still stinks. Mateo is on the hottest streak of his short career: After 16 games, he has a 192 wRC+ and 1.1 WAR, tying him for third and fourth in baseball, respectively. Naturally, he wasn’t going to be able to keep this up for a whole season; he has a .378 BABIP, and his wOBA exceeds his xwOBA by 59 points. It’s April 20, and the regression monster is laying in wait right for him right now.

But that’s part of what makes his hot start so fun. This is Jorge Mateo! The light-hitting, glove-first speedster. He was a fun player when he was just stealing bases, making jump throws from the hole, and trying to beat out infield hits. All of a sudden he’s got a .638 slugging percentage. In the last 16 games, he’s raised his career wRC+ by 9%. Obviously, I’m going to examine whether any of this looks sustainable, but first let’s take a moment to enjoy what we’re seeing while spring is in the world.

You know who’s definitely enjoying Mateo’s hot start? His Baseball Savant sliders, which are really fulfilling their purpose:

Now that we’ve had our fun, it’s time to pay attention to the syntax of things. At first glance, it might look like Mateo isn’t doing anything that new. Below is a graph of his wRC+ over the course of his career. You can see that he’s had some very hot stretches in each of the last two seasons.

As recently as last year, he had a longer stretch where he hit nearly this well. Over the 23 games from July 27 to August 18, Mateo put up a wRC+ of 172, peaking at 197 on August 12. All the same, even a cursory glance at his top line stats reveals some exciting changes:

Jorge Mateo Stats
Season G PA HR BB% K% BABIP wOBA xwOBA
2022 150 533 13 5.1% 27.6% .286 .281 .272
2023 16 57 3 8.8% 15.8% .378 .444 .385

Mateo is definitely outperforming his expected stats, but those expected stats are still way, way up. His walk rate is also up significantly from last year, and his strikeout rate is down a massive 11.8 percentage points. His strikeout rate did dip this low during last year’s hot streak, but his underlying metrics didn’t change the way they have this year.

Let’s start with his plate discipline. By Baseball Savant’s swing/take runs metric, his decision making has been worth 4 runs this year, up from a disastrous -16 last year.

Jorge Mateo Plate Discipline
Season O-Swing% Z-Swing% Swing% Contact% SwStr% CStr% CSW%
2022 39.4% 72.8% 53.1% 71.0% 15.4% 14.5% 29.9%
2023 27.2% 67.4% 44.2% 77.1% 10.1% 17.9% 28.0%

Mateo is swinging a lot less overall, but the drop in his chase rate is particularly big. That means more called strikes, but fewer strikes overall. The result is that 33.6% of the pitches he has seen came when he was ahead in the count, up from 22.1% in 2022. During that 23-game hot stretch from last year, his chase rate didn’t change much at all.

This is truly something new for him, and here’s why it matters so much. There are three heat maps below; the one in the middle is Mateo’s career ISO per batted ball. He should be swinging anywhere it’s red, since that’s where he can do damage. On the left is his swing rate from 2022, and on the right is his swing rate so far in 2023:

That’s a huge difference! Last year, Mateo swung at pretty much anything close to the zone, except for the outside edge. This year, he’s not just being more passive, and he’s not just chasing less. He’s laser-focused on the pitches that he can crush, and he really is crushing them. For some players, getting less aggressive can lead to a dip in contact quality; not so for Mateo. Take a look at his batted ball metrics:

Jorge Mateo Contact Quality
Season EV maxEV LA Barrel% HH% GB/FB HR/FB Pull%
2022 86.8 111.3 14.8 5.9% 32.5% 0.92 9.1% 36.6%
2023 92.2 112.4 7.0 7.1% 45.2% 1.82 27.3% 47.6%

Mateo isn’t just hitting balls hard; he’s demolishing them. He just hit the hardest ball of his career, and of his 19 hard-hit balls this year, all but two were hit over 100 mph. How new is that? While he had two 2022 stretches with with a hard-hit rate this high, he’s never had stretch with a 92.2 mph exit velocity before, and he’s never come close to hitting 42.5% of his BIP over 100 mph (in my Jorge Mateo spreadsheet, that column is titled Demolish Rate).

The other development is less inspiring: Mateo is hitting a ton of groundballs. He’s cut his launch angle in half, and even for a player with his speed, that’s not great news. But as Ben Clemens wrote on Wednesday, “If you’re hitting the ball on the ground a ton and not hitting it hard when you do put it in the air, that’s bad. If you’re making loud aerial contact, that’s good.” A 27.3% HR/FB rate is unsustainable, but break down Mateo’s numbers and it becomes apparent that he’s making the most of his contact in the air:

Jorge Mateo Fly Balls and Line Drives
Year Number wOBA xwOBA EV Pull% Distance
2022 185 .519 .486 91.2 28 278
2023 17 .741 .650 97.3 59 283
SOURCE: Baseball Savant

Mateo is hitting the ball farther and significantly harder, and his xwOBA on air balls is up 164 points. He’s still outperforming it by quite a bit, but keep in mind that expected stats don’t take spray angle into account, and since the beginning of the Statcast era, pulled balls in the air have had a wOBA 129 points higher than their xwOBA. Mateo’s pull rate on air balls is a huge 59%, which means there’s less luck behind this performance than you might think.

Coincidence or not, all of these changes are happening as Mateo is breaking in a slightly revamped batting stance. Last year, he used an open stance, with his shoulders starting out rotated further away from the pitcher than his hips. His swing also had a pretty standard leg kick. This year, his body is right in line with the pitcher, and he uses a two-part timing mechanism that’s something like a deconstructed toe tap. He narrows his stance by drawing his front foot back, pauses for a moment with it flat on the ground, then steps forward and very slightly toward the third base side, opening up just a hair. Mateo has always appeared to keep a lot of his weight on his front leg; I’m not an expert, but to me it looks like the new stance allows him to be a bit more balanced, keeping his weight back longer and generating more power with his back leg.

I should probably admit that the original title of this article was, “Jorge Mateo Is Never Gonna Die.” It was pointed out to me a few hours before Wednesday’s game that I might be jinxing Mateo, so it’s possible that his injury is my fault. “I’m never gonna die,” is what a character in a comedy says right before they get hit by a bus or something. My point was that Mateo was going to come back to earth at some point. And I know I’ve spent the last 1,500 words or so cataloging all the different ways that he looks like a different player, but we’re still talking about just 16 games and 57 PAs. He is not in fact going to live forever, though I doubt hip discomfort will be the thing that takes him down. He’s always struggled against fastballs, and so far he’s fared worse than ever against pitches at or above 95 mph. He’s also seeing more fastballs than ever.

But while I don’t think Mateo is going to maintain a 68th percentile chase rate or an 86th percentile average exit velocity, I am willing to believe he’s better now than he was last year. Here’s the more important part: He doesn’t need to improve much to be a great player. Mateo is an excellent shortstop. He may not have hit well enough to be a Gold Glove finalist, but whatever your preferred defensive metric — OAA, DRP, DRS, UZR, that weird one where you just look with your eyeballs — it adored him in 2022:

Jorge Mateo Defensive Metrics – 2022
Metric Value MLB Rank
DRS 14 3
UZR 7.4 2
OAA 11 4
DRP 4.8 11
Eye Test High Also High

In fact, if you take the average of all four metrics, Mateo’s score of 9.3 is second in baseball, behind only Dansby Swanson. If you take the average of each player’s rank in each system, he comes out first. This is a convoluted way of saying what Leo Morgenstern said last year: Jorge Mateo deserved a Gold Glove. And excellent defensive shortstops don’t need to contribute much on offense to provide value. He just put up 2.8-WAR season despite a wRC+ of 82. Even if he holds onto just a fraction of these gains, a tiny improvement in contact quality or plate discipline could make him a league average hitter, and therefore an All-Star caliber player.

Further, Mateo is one of the fastest players in baseball. His 5.8 baserunning runs put him in a tie for the 15th-most valuable runner in baseball last year. He led the American League with 35 steals, and his eight so far this year trail only Cedric Mullins and Nico Hoerner. That is to say, every little bit of on-base ability he can add will get compounded because it will allow him to produce more value on the basepaths, too.

Even after you strip away the batted ball luck, Mateo’s performance thus far is extremely encouraging. I am hoping fiercely that this hip injury is nothing major, and that he gets the chance to ride this hot streak as far as it’ll take him.





Davy Andrews is a Brooklyn-based musician and a contributing writer for FanGraphs. He can be found on Twitter @davyandrewsdavy.

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Kvnmember
10 months ago

Been waiting for someone to write about this. I’ve watched a lot of Jorge Mateo at bats these last few years and his increased patience is noticeable. I think people have this perception that he has no power, but in reality he historically has made such bad swing decisions that he never got to any of it. I think even if his defense backs up a bit “Jorge Mateo but with a league average OBP” is legitimately a 4+ WAR player and I really hope he stays healthy enough to see if he can pull it off.

sadtrombonemember
10 months ago
Reply to  Kvn

A Jorge Mateo with those walk and strikeout totals goes from “bridge to Gunnar at shortstop” to “hangs out until Jackson Holliday is ready to take over.” He’s a bit of a risky long term bet because so much of his game is riding on his speed but in the medium term he would be awesome,