Seattle Mariners INF Joseph Rosa Scouting Report, 2017

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

TOOL (FV)

NOTES & COMMENTS

Hit (50)

Good feel for barrel manipulation from both sides of the plate to hit line drives gap to gap; generally more productive and comfortable from the left side. Tracks pitches well; advanced pitch recognition for his age. Will struggle with some swing and miss, particularly from the right side of the plate, but full coverage with an approach to all fields and should be a line drive machine as he grows into his body and develops stronger hands and wrists. Will benefit from continuing to play every day but eventually must work into utility role with infrequent at-bats and consistent approach.

Power (40)

Not a power hitter, but he’s going to surprise with some pop — not as much over-the-fence work as gap-to-gap doubles, but good bat speed with feel for lift and some natural strength will combine to produce some sneaky power. In time, as he grows into his body (still just listed at 165 lbs. as a 20-year-old), think he can develop into all-around hitter with some pop. Best attribute is his attacking nature; looking to do damage in the air even now, and will hit the ball hard when he squares it up.

Glove (55)

Slick fielder with good feel for lateral movement to both sides on ground balls; soft hands that can play shortstop right now with ease. Arm lags a little bit (more below) but enough glove to play anywhere in the infield. Intense; natural leader on the field with good awareness and anticipation; competitive and will outplay utility projection for as long as he can through minors.

Arm (45)

Lacks ideal arm strength to play shortstop everyday; part of it is in lacking physical size; still underdeveloped and has a tough time on occasion putting up necessary velocity and carry from left side of the infield, particularly through backhand. Could function anywhere on diamond in short-term utility role, but unlikely to stick at shortstop in everyday job in upper minors and beyond without significant arm strength bump.

Speed (55)

4.17 up the line from LHH box; 4.29 up the line from RHH box. Lateral quickness with great first step; gets out of the batter’s box well and moves up the line; intense competitor who hustles out balls in play. Moves well in the field, gaining ground beyond what you’d expect from a player his size and shows very good reaction times off the bat. Plays bigger and quicker than you’d think, which speaks well to his competitiveness and overall athleticism.

Intangibles

Gamer; intense competitor who has been challenged the last few years with short-term assignments at high-level full-season leagues and proven himself well. Potential jack-of-all-trades future as a super utility athlete all around the diamond. Bat is more developed than I expected it to be. Good sleeper pick to move fairly consistently and have a big league impact one day if he finds the right role and fit on a 25-man roster.

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