Julio Rodríguez’s season was growing bleaker and bleaker by the day as he labored through the longest slump of his short career. We had expected him to get right sooner than later — after all, he’s one of the most talented players in the sport, with an explosive bat, top-shelf sprint speed, and a cannon of an arm — but it was worrisome to see him struggle for so long.
He had an 86 wRC+ across 360 plate appearances at the end of June. Over the last few months, though, Rodríguez has progressively figured things out, with his turnaround culminating with his current heater. Since July 1, he is batting .321/.377/.545 with 12 home runs and a 166 wRC+, and over his last 10 games, fueled by his .458/.471/.833 line, five homers, and 270 wRC+, he’s added 1.3 WAR to his ledger.
He is a key reason why the Mariners are still in the playoff race with less than a week remaining in the season, though you could also make the case that his overall underperformance is one of the reasons why Seattle is barely hanging around. Either way, to better understand the story of Rodríguez’s season, we have to dive deeper into his struggles.
Rodríguez pitch-by-pitch performance data show he spent the first three months of the season almost exclusively hunting fastballs, which isn’t a bad idea considering he feasts on them. The problem was that because his eyes were focused only on one speed, he started swinging at any pitch that he thought might be a fastball, and as a result, he was chasing too many breaking balls and offspeed pitches.
| Pitch Group | Pitch% | xwOBA | xSLG | Whiff% | Zone% | Chase% |
|---|---|---|---|---|---|---|
| Before July Fastball | 52.1% | .383 | .525 | 23.9% | 49.9% | 32.3% |
| Since July 1 Fastball | 53.8% | .429 | .617 | 24.0% | 53.6% | 35.6% |
| 2024 Total Fastball | 52.8% | .400 | .558 | 23.9% | 51.4% | 33.5% |
| Before July Breaking | 35.3% | .285 | .359 | 38.3% | 37.5% | 37.5% |
| Since July 1 Breaking | 34.2% | .350 | .503 | 36.8% | 40.8% | 35.6% |
| 2024 Total Breaking | 34.9% | .313 | .419 | 37.7% | 38.7% | 36.8% |
| Before July Offspeed | 12.6% | .207 | .248 | 39.3% | 36.8% | 54.9% |
| Since July 1 Offspeed | 11.9% | .268 | .336 | 34.4% | 36.8% | 41.8% |
| 2024 Total Offspeed | 12.3% | .233 | .284 | 37.6% | 36.8% | 50.0% |
SOURCE: Baseball Savant
During the first three months of this season, Rodríguez may have been the worst everyday hitter against offspeed pitches in the entire sport. Among the 260 batters who saw at least 50 offspeed pitches outside the zone through the end of June, he had the second-worst chase rate at 54.9%, behind Nick Gordon. As a result, Rodríguez had a .157 wOBA against offspeed pitches, which dragged down his overall numbers, especially because he also had trouble against breaking balls (.232 wOBA).
Rodríguez’s feast-on-fastballs approach corresponded with a swing deviation that limited his production. In previous seasons, Rodríguez thrived because of his swing variability, which allowed him to do damage against different pitches in different locations. That is an essential skill for him because he is one of the more aggressive hitters in baseball. However, during the first months of this season, because he seemed to be selling out for fastballs, his hacks were too noisy on most of his swings.
That type of one-dimensional swing is designed to crush higher-velocity meatballs — and, even as he struggled, he was still doing that — but it is susceptible to pretty much everything else. When looking at SEAGER, it becomes clearer that Rodríguez truly did have an eat-the-meatball approach. Yet despite his increased chase rate against offspeed pitches, his SEAGER has actually improved from last year. His Selectivity% is about league average as of this week, in the 54th percentile (mainly due to recent improvements), but his Hittable Pitch Take% is in the 97th percentile, meaning he is rarely letting pitches he can damage pass him by. Altogether, he is in the 95th percentile for SEAGER, a jump from last year’s 69th percentile score.
At first glance, this might seem contradictory, that he’s making better swing decisions during his worst season. But just because he is swinging at hittable pitches doesn’t mean those swings have enough variability to produce against pitches with different speeds and locations.
The thing is, even though Rodríguez was hunting heaters with a swing that is tailored to damage them, it doesn’t seem like he intentionally altered his mechanics. Rather, the two changes likely came about simultaneously and spiraled as they reinforced each other. Here’s what probably happened: After getting off to a slow start, he began pressing to break out of his funk and tried to clobber the most hittable pitches he saw, leading to a one-dimensional, fastball-dependent swing.
Rodríguez is at his best when he has a flatter Vertical Bat Angle (VBA). VBA is the angle of the barrel relative to the ground at contact. So that means his best performance has come when his bat has been flatter at contact. That could mean deeper contact and/or a flatter entry into the hitting zone. Flat swings don’t work for all hitters, but for someone like Rodríguez who creates so much bat speed deep in the zone, they typically are a recipe for success.
Over the first three months of the season, Rodríguez had the steepest VBA of his career, ranging between 33.4 to 35.5 degrees; this stretch coincided with his below-average offensive production. Since the beginning of July, though, he’s flattened his VBA to somewhere between 30 and 31 degrees, much more in line with his career norms.
Rodríguez’s upper body mechanics are crucial to his swing because they determine the path his bat takes to the ball. He has a louder bat row, similar to those of Vladimir Guerrero Jr. or Rafael Devers, two hitters who also have swings on the flatter side.
Noisy movements help batters generate power and time up their swings, but with more movement comes more room for error when something goes awry. Having an effectively loud swing requires maintenance and attention to ensure the delicate balance between power and control doesn’t fall out of whack.
If Rodríguez’s swing had unintentionally become more vertically oriented because of a different setup or row, that could have disrupted where he perceived his bat to be in space (proprioception) and hindered his contact quality and frequency.
This all makes sense in theory, but let’s confirm it with some video analysis. The first two swings below are from May and the next two are from July:
Now, let’s compare two swings, one from last season when he was rolling, and another from the second half of this season, as he returned to form:
His mechanics aren’t identical, but they are much closer now than they were when he was struggling during the first few months of this year. Pay attention to the angle of his bat throughout the row and how far his hands drift from his body. Maintaining the connection between his barrel/hands and the rest of his upper body is paramount for him to control his barrel.
As a last piece of information to consider, I was curious about how Rodríguez’s bat speed changed as his row calmed down a bit and his swing flattened back out. This month, his bat speed has ticked up significantly compared to the first three months of the season. He’s swinging at an average velocity of 77.7 mph in September, a sizable spike from April through June, when his average swing was just under 76.0 mph. If flatter means faster, then it sounds like he should stay where he’s at right now.
Any Mariners fan would tell you that in the first few months when Rodríguez was struggling, he was clearly pressing. Any player would tell…
