Tall, thin, very skinny; will need to add weight but narrow shoulders may not allow for much growth
4/27/15, 5/4/15, 5/11/15, spring training
St. Lucie Mets (High A, Mets)
50, everyday regular
Big swing with some length, good extension on finish but needs to shorten bat path to ball; above-average bat speed; up-the-middle approach, aggressive mentality; pitch recognition issues, doesn't recognize change-ups out of pitcher's hand; doesn't make consistently solid contact.
Some pop for a thin guy generated by bat speed and strong wrists; some power to shoot gaps but not over-the-fence power; could hit for moderate doubles power in prime; will never be an impact, middle-of-the-order hitter.
More first-step quickness than straight-line speed; gets to top speed quickly but not a plus runner.
Incredibly smooth actions in infield, works through the ball extremely well; attacks ball, rarely back on his heels; plus range at present, could get to plus-plus with footwork development; creative fielder, will go behind back, underhand, etc. when situation dictates; can get too fancy and make mistakes on routine plays, which comes with youth and inexperience - not a long-term problem.
Ideal shortstop arm, quick release for a long-armed player, can throw from all arm angles and still generate strength; throws carry well across diamond; can make all necessary throws to be a plus shortstop.
Rosario shows some promise with the bat, but doesn't make consistently hard contact and doesn't drive the ball. At his peak, he should offer some doubles power, but will never be a big over-the-fence contributor. His aggressiveness at the plate can be improved upon with age, but is also a part of his mentality as a player and thus likely doesn't have a ton of room for growth. That aggressiveness limits his swing utility and should ultimately cause him to be a down-in-the-order hitter unless he proves to have better contact skills than he's presently showing.
Rosario is a fantastic shortstop, which will be enough to carry him to the big leagues. He has a chance to be a plus defender at a premium position, and will be able to remain at the position for the majority of his career. That lowers the bar on his bat, which should be good enough to be an everyday player but won't be of the impact variety. With his defense, that won't matter.
The common assumption is that he will add weight onto his thin frame as he grows, but his narrow shoulders and slight build don't allow for much room for growth. This isn't a player who is going to fill out significantly and pack on substantial pounds. He'll get stronger, but only incrementally, which will keep his power in the gaps rather than over the fence. It will also keep him from having to move off of shortstop, which is ultimately more important.
There is still a lot of room for growth with Rosario, who is still just 19, but unless he significantly improves his contact skills and feel for the barrel, he won't be an impact hitter. His defense is strong enough, however, to be an everyday player and an extremely good shortstop, and with the bar being where it is for shortstops offensively, reaching 45/35 with plus defense could still put him in the top half of shortstops in the league.