A slick fielding middle infielder who started his career with the Dominican Summer League Mariners as an 18-year-old in 2015, infield prospect Joseph Rosa spent the bulk of the 2017 season with short-season Everett in the Northwest League, also logging time at three other affiliates with the Seattle Mariners and splitting time between shortstop and second base along the way. A switch-hitting 20-year-old (DOB: March 6, 1997), Rosa slashed .276/.358/.477/.835 in 214 total at-bats in 2017, with 17 doubles, four triples, six home runs, seven stolen bases, 27 walks, and 49 strikeouts over 54 games.
A jack of all trades with good athleticism and defensive feel for both spots up the middle, Rosa is advanced for his age with the glove and could move fairly quickly through the system as a utility infielder with role player upside in a bench job. Further offensive development could land him on a 25-man roster in a few years, as the Seattle Mariners could benefit from a versatile defender with matchup capabilities and a little bit of line drive punch in his bat at the plate. Below, Baseball Census has a full Joseph Rosa scouting report, including tool grades, game video, and projection notes.
Joseph Rosa Scouting Report, Seattle Mariners — 2017
Dates observed in 2017: August 1-3
Joseph Rosa Scouting Report, Seattle Mariners — 2017 Game Video
Joseph Rosa Scouting Report — Notes, Analysis & Projection
The Seattle Mariners have a sneaky-good prospect in Joseph Rosa, who I believe has the natural athleticism and baseball acumen to become a super-utility player capable of splitting time among multiple infield and outfield positions while matching up with the bat from both sides of the plate. He’s more advanced with the bat than most 20-year-olds in the Northwest League, and there’s a competitiveness to Rosa that should make him a natural leader as he moves up the ranks. He’s not a physical specimen and lacks easy upside in an everyday role, so it’s unlikely you’ll find him on any Seattle Mariners prospect lists moving forward, but there’s some raw talent here that could be developed into the right kind of utility/bench guy if things fall into place. Expect him to spend 2018 at Low-A Clinton, with a shot to cameo (or more) at Modesto by the end of the year.
Overall Future Potential (Future Value): Jack-of-all-trades type utility infielder/outfielder in the making; bench role with versatility value on 25-man roster (40/45)
MLB ETA: 2021
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