Julio RodrĂguez has time to kill (more fly balls).
Julio is one of the 10 best defensive centerfielders in MLB. He finished seventh in 2025 with 11 OAA; he’s second since his debut with 38 OAA. It’s the skill that separates him as one of the best young players in history.
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How long can he keep it up?
We know how batters age at the plate. They tend to peak by wRC+ from age 26 to 29 and drop off slowly (and then quickly) thereafter. Phenoms hang on a bit longer. This is great news for Julio, who’s already one of the 20 most valuable hitters in MLB and doesn’t turn 25 for two more weeks.
For this post, however, I wanted to know how Julio might age on defense. I created an aging curve for centerfield defense using OAA from Baseball Savant. I limited the sample to all qualified centerfield seasons since 2016. Here we can see average OAA (and OAA per attempt) for centerfielders by age:
OAA drops with age. We see an early peak and plateau through age 25, and then a relatively steep decline thereafter. Julio appears to be conforming to this trend, reaching the mid-20s plateau firmly above average. This next plot shows year-over-year changes in OAA (a true aging curve) among qualified centerfielders:
I also did this with Savant’s “jump” metrics, which measure how much distance a fielder covers in the first three seconds after amball is hit. It’s strongly correlated with OAA. We can see Julio’s jump was about average in 2025, though he’s consistently collected more outs than implied in his jump. Perhaps this suggests the presence of an additional skill (like the act of physically catching the baseball into the glove); or perhaps this says something about T-Mobile Park’s tendency to suppress carry distance.
Jump is made up of:
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- Reaction (distance traveled from 0 to 1.5 seconds)
- Burst (distance traveled from 1.6 to 3 seconds)
- Route (directness to the ball)
Burst is the most important by far. I like to think of it as the skill-ified version of sprint speed — how quickly can a player access their top gear while tracking a baseball. Compared to other centerfielders, Julio is both fast and efficient:
This is one of my favorite features of Julio’s game. I love those plays where the opponent laces a low fly ball into the gap, the camera flips and its Julio, a flash of magenta, barreling towards the wall, not quite graceful like Guti or liquid like Saunders, but ferocious, tenacious, reaching his target with a spectacular pounce and roar. It’s threatening. Do not fly here.
This is also likely the first feature we’ll see disappear from Julio’s game. Again, burst correlated with sprint speed, and both tend to drop off immediately.
Reaction and route are more nuanced. We can see these skills are negatively correlated, meaning the faster the reaction, the worse the route.
Julio falls into the strong route, poor reaction category; he was top/bottom 10 in both in 2025. This doesn’t matter too much — burst actually tells us slightly more about OAA than total jump — but it is indeed the lesser of the styles. For every foot an outfielder gains with their route, they lose nearly two feet with their reaction. It’s often better to simply take off in the direction of the ball and figure it out later. If there’s something limiting Julio from achieving even more in the outfield, it’s likely this tradeoff.
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Unlike burst, reaction and route change less predictably with age. Reaction declines slightly, though further testing suggests there’s no pattern. Route on the other hand improves with age. It’s not clear whether routes actually get better with experience (this makes sense), or if poor route runners are just the first to get filtered out (this also makes sense). Regardless, we can see Julio has already taken a tremendous leap in route running, with a similar decline in reaction.
Finally, Julio has a strong arm for a centerfielder. He’s not particularly accurate, and controlling the base paths is not a big part of his game. Still, he tends to nab a few runners each year and generally discourages taking the extra base. Arm data is newer so it’s hard to say how it changes with age; I found no pattern in arm value with age in limited data.
Julio is a great defensive outfielder. I think he could potentially play at this level for two or three more years. I don’t think we’re ever going to see him post Platinum Glove numbers, and I wouldn’t say he’s even a top five fielder at the position. But he seems to have some knack for the position that could allow him to better withstand age-related decline in athleticism. I expect him to be the Mariners’ centerfielder for many years.
