One of the top athletes in 2016’s J2 class, Rosario signed with San Diego for $1.85M. Still just 18-years-old, he handled much older competition in the Class A Midwest League for the entirety of this season, slashing a very respectable .271/.368/.353 slash line in 117 games for Ft. Wayne.
Built with a medium frame that’s oozing athleticism and projectability, Rosario looks the part of a big league centerfielder. He’s a plus runner (4.15-4.21 times up the line) with wheels that show up on the bases and in the field. Rosario covers ground in the outfield with an easy glide, ranging well to both sides and showing the physical tools to be an above-average defender. He closed the gaps better than he went back on balls over his head in my look, but that’s a route running issue that can be ironed out with time. Offensively, Rosario is a contact-oriented hitter with plus bat-to-ball ability. He didn’t whiff much for a player his age in full-season ball, and projects to be the type of hitter that puts the ball in play and pressures the defense. I was impressed with Rosario’s sense of the strike zone, as he showed ability to lay off close pitches and recognize spin. There isn’t much power right now, and parts of his swing mechanics—namely, a bent upper-half that shrinks his strike zone but takes away leverage—don’t lend themselves well to lifting the ball.
Even if he’s always light in the power department, Rosario has the ceiling of at least an everyday centerfielder given his four other strong tools. Players who compete like he did at such a young age often come back radically different players at age 19 and 20, so it’s too early to fully slap the “slappy singles hitter” label on Rosario. If he grows into average power, his ceiling could wind up being as high as a FV 55 type. He’s as old as most college freshman and will start 2019 in High A.