In 2017, Amed Rosario was the #1 prospect in baseball. He bludgeoned Double-A, was solid in Triple-A, but then underwhelmed in the majors for 170 PA. Nevertheless, there was significant excitement around Rosario entering 2018, as he represented the first potential long-term SS for the Mets since Jose Reyes left in 2011.
Instead, many of the same struggles that plagued Rosario persisted into 2018. He continued to be a free swinger, with a 41.2% O-Swing% that was the ninth highest in baseball. The batted ball profile remained underwhelming, with Rosario beating the ball into the ground nearly 50% of the time and sprinkling in a higher percentage of infield fly balls. Rosario’s hard hit rate didn’t significantly improve either, and his ISO actually decreased to an even more pedestrian .125.
That’s not to say there weren’t improvements. Despite a poor stolen base success rate at 24 out of 35 (69% - nice, but not above the break even point), Rosario improved the rest of his baserunning to add five runs of value over the course of the season, a marked improvement over 2017. Further, his stolen base rate improved dramatically in the second half, with 18 steals in 24 attempts after only six successful attempts in 11 tries in the first half. Amed’s got blazing speed, and that’s a significant improvement in a skill that he should have.
With the bat, there were some positive signs as well. His contact percentage improved drastically, both in and out of the zone, and Rosario’s strikeout rate dropped from an unmanageable 28.8% to a reasonable 20.1%. The improved ability to make contact also boosted Rosario’s walk rate to a mediocre-but-not-abysmal 4.9%, and raised his overall batting line to .256/.295/.381.
Unfortunately, that’s simply still not very good. The slightly improved patience and significantly improved contact was only enough to get Rosario up to an 85 wRC+, the same mark posted by Tim Anderson and Freddy Galvis, tied for the 15th best rate among qualified shortstop. There was a slight uptick in the second half - 90 wRC+ - brought on by an improved BABIP due to a slightly higher line drive percentage and a slightly lower infield fly ball rate. The sample size on that improvement is not significant, however, and it wasn’t a big improvement to begin with.
Defensive metrics were also not kind to Rosario this season, culminating in a -5.6 UZR/150 and a whopping -15 DRS, the second worst mark in baseball this season. These numbers are flawed, arguably a better measure of positioning than defensive talent, and not reliable on a season-by-season basis, but Rosario did not appear to be a standout defender by the eye test either. The sub-par offense combined with the bad defensive numbers led to a meager 1.5 fWAR.
The 22-year-old Rosario is anything but a finished product, and it’s far too early to give up on him as a long-term fixture. For now he’s a serviceable everyday shortstop with enough upside to merit his continued presence in the lineup even if the results aren’t there. He’ll need to make significant strides at the plate, either in terms of power or patience, in order to make good on that upside.