Amed Rosario's much-anticipated debut was for many Mets fans the lone highlight of an otherwise brutal 2017 season. The former top prospect arrived in Queens on August 1 to sky-high expectations, some of which he met and some of which he did not. Going into 2018, his age-22 season, it may not be fair to anticipate a superstar breakout, but there are a number of ways he can improve and grow.
As many expected prior to his debut, Rosario's bat is still very much a work in progress. His .665 OPS would have been the fourth-worst among shortstops in 2017 if he had enough plate appearances to qualify. It's hard to find a silver lining in his performance, other than the fact that he's still very young and can largely be carried by his glove. Plate discipline, power, and baserunning all need work, even for someone who brings elite defense to the table.
No one was looking for Rosario to be a walk machine at the plate, but the three bases on balls he drew over his two months with the Mets were good for a 1.8 percent walk rate, the lowest in the majors of all 435 players with at least 100 plate appearances. Paired with a strikeout rate close to 30 percent, it's crystal clear that improving his plate discipline needs to be Rosario's top priority in preparing for the new season. He's never going to be Brandon Nimmo up there, and he doesn't need to be, but a swinging strike rate nearly double the league average is a problem.
The good news is that simply maturing and settling in to the rhythms of big league-level play should make up some of the difference automatically. ZiPS and Steamer projections both expect Rosario to walk somewhere between 4 and 5 percent of the time -- still very low, but not alarming so -- and for the strikeout rate to plummet to around league-average 20 percent. Those adjustments, not a huge reach to expect, will get his on base percentage up to .300, which should be one of his big goals for the year.
Rosario has never been expected to be a power threat, but he did manage to knock four home runs in his partial season last year. That puts him on track for roughly 12-to-15 in a full season, slightly more than he is currently projected to hit in 2018. He is never going to be a slugger, and certainly shouldn't make major changes to his approach to try to become one, but coming to the plate with even a slight chance of hitting one out can change a pitcher's approach in a very favorable way (especially if he also cuts down on the wild swings).
While Rosario brings great speed to his game -- a gift that will help bolster his batting average even if he continues to struggle with patience at the place -- he hasn't yet managed to distill his physical capability into gameplay. Fangraphs put his overall contribution on the basepaths right about league average. It's based on a small sample, but his 30 percent caught-stealing rate needs some work, and he also needs to better identify when to be aggressive. Much of this is a function of his youth. An extra year and some time with the big league coaching staff will do him a lot of good.
Rosario came to the Mets with a stellar glove and that glove will ensure that he has a place on the field for a long time. The bat is what has the potential to make him a star, though. And while his 2017 was not the most encouraging debut, the potential is still very much there. He will come into 2018 with something to prove.
Maggie Wiggin (Facebook | Twitter | Instagram | Archive Posts) has been a Mets fan since birth and a MetsBlog contributor since 2013. She loves throwing hard and hitting hard and hates the DH. When baseball is out of season, she fills her days with data analysis and evaluation and patiently waits for Spring