Ever since Rosario signed for $1.75 million in July 2012, he's impressed not only with his physical tools, but with a maturity well beyond his years. That's a big reason why the Mets have always pushed him aggressively, starting with allowing him to make his pro debut at age 17 in the United States and up in the Rookie-level Appalachian League. He was three and a half years younger than the average position player in the league that summer of 2013.
That's been the rule, not the exception, as he reached Double-A, albeit briefly, at age 19, in 2015. Through that season, while more than holding his own given his age, Rosario had not put up particularly noteworthy numbers. It was in 2016 where his production caught up with his potential as the phenom hit a combined .324/.374/.459, splitting the year between the Class A Advanced Florida State League and the Double-A Eastern League, where he was 4.3 years younger than the average.
That likely started the "When will he be ready?" questions in earnest. The move up to Triple-A at age 21 (5.4 years younger than average) brought that up to a roar, especially as he put up a .328/.367/.466 line. The Mets resisted, until now, having circled the first week of August as the likely best time for that first callup, giving him the chance to get his feet wet away from the New York spotlight.
Not that Rosario will have any difficult dealing with that glare. Even if he doesn't produce right out of the gate, there's little question he'll be able to handle the attention and expectations with the same even-handedness he's shown throughout his professional career. And the guy is going to hit. He has an innate knack of making consistent hard contact and can use all fields. He has some extra-base ability now, and there is more power to come, keeping in mind that he is still physical maturing. His plus speed should allow him to continue being a basestealing threat (19 in 2016; 19 at the time of his callup in 2017).
And we haven't even gotten to his defensive game yet. That speed gives him plenty of range to go along with his plus hands, footwork and an arm that is both strong and accurate. In other words, he's a shortstop long term, not one of these prospects who'll outgrow the position or who has a defensive deficiency that will force a move to second, third or the outfield.
Major League Baseball has enjoyed ushering in a new era of exciting young shorstops of late, All-Star caliber players like Carlos Correa, Francisco Lindor, Xander Bogaerts and Corey Seager. Rosario has every chance to be part of the next wave, with a ceiling every bit as high as this young, but already accomplished, group.
The exciting thing for those looking at the future of the Mets is that there's more to come. First base prospect Dominic Smith, himself having a phenomenal season in Las Vegas, could very well join his teammate in the very near future.