Amed Rosario: Teenage Breakout Candidate

Analyzing prospects in short-season leagues can often be a confusing and fruitless endeavor. All three of pro baseball’s three large development hurdles–the jump to full-season ball, the jump to the upper minors, and the jump to the majors–remain in front of such players, and projecting how raw 17-21-year-olds are going to handle those difficult transitions years down the line cannot be done with much certainty. Still, there are plenty of relevant prospects in the short-season circuits, and today I’m going to discuss the first of a few that I personally viewed in the Rookie-Advanced Appalachian League in 2013: Mets shortstop prospect Amed Rosario.

Rosario had the distinction of being named the top prospect in the Appy by Baseball America, which immediately pegs him as someone to watch. So does his birth date: November 20, 1995. He was the youngest position player to open the year at the Rookie-Advanced level, which says a lot about how advanced he is for his age, even if the numbers he posted (.241/.279/.358 with a 43/11 K/BB, 3 HR, 2 SB, and a .941 fielding percentage in 58 games) veer closer to “problematic” than “exciting.”

But a player’s ranking on prospect lists and his raw numbers (particularly at such a low level at such a young age) do little to shed light on what sort of player he may become. For that, we have to turn to visual evidence.

Okay, three fielding plays and seven plate appearances isn’t exactly the most complete visual evidence, but it’s a starting point, and there’s quite a bit that can be gleaned from this.

First off, Rosario has an athletic 6’2″ frame–his listing of 170 pounds is probably fairly accurate, though he may be closer to 180 at this point. Either way, he has natural athleticism and fluid actions, and he still has plenty of room to fill out and add strength to his frame. He’s not a burner type, as evidenced by his 2-for-5 showing on the basepaths this year, but there are plenty of guys who stick at shortstop without plus straight-line speed–think of Andrelton Simmons, Yunel Escobar, J.J. Hardy, Zack Cozart, Pete Kozma, Troy Tulowitzki, Stephen Drew, Brandon Crawford, or Jhonny Peralta, who all stole single-digit numbers of bases this year but were above-average defensive shortstops per UZR. You can see from the video that Rosario is not without range, and he has a playable arm. Like many young teenage infielders, his biggest defensive issue is a tendency to try to do too much, attempting to make difficult throws on plays that he doesn’t have a shot at the runner. The .941 fielding percentage looks bad, but it’s not out of the ordinary for players at this level–it ranked ninth out of the thirteen Appy shortstops who played at least 20 games at the position, and had he fielded .942 instead of .941, he would have been tied for seventh. Given how much younger Rosario was compared to almost all the other shortstops in the circuit, being at the back of the middle of the pack in error rate isn’t bad.

While it’s too early to say that he’ll definitively stick at shortstop–so much of that depends on how his body evolves–it’s safe to say that Rosario will have some defensive value. At worst, he’s probably an average defensive third baseman, which would still give him a slightly positive FanGraphs Defense number.

What about the other side of the ball, though? Obviously, projecting to be solid or better with the glove is nice, but Rosario’s going to have to hit a whole lot better than .241/.279/.358 to be much of a contributor. A .295 wOBA doesn’t exactly scream “impact player” regardless of position, especially for fantasy purposes.

But then you see this…

…and it’s easy to discount the mediocre production.

That’s Rosario taking a 91-mph first-pitch moving fastball on the outer half from Clayton Crum and driving it out of the ballpark to the opposite field. You don’t see players do that much even in Low-A, let alone at the Rookie level, and it’s especially intriguing to see such a display from a player so young and who isn’t just a big power masher type.

Watch how long Rosario waits before he starts his swing. He has very impressive bat speed, and thus can sit back on pitches for much of their flight path and still get his bat to the ball. They say “you can’t walk off the island,” and Rosario’s 4.9% walk rate might paint him as an adherent to this dogma, but his approach actually seems fairly patient–he offers at just nine of the 23 pitches in the video. He also struck out just 19% of the time, a testament to his advanced ability to make contact. His .118 ISO isn’t too bad for a shortstop, and power could become a significant element of his game as he continues to settle into pro ball and refine and develop his swing, approach, and skillset.

What holds Rosario back right now is inconsistency in a number of areas. If power is going to be a major force in his game, he’s going to have to turn on the ball more. Most of his contact in the video seems to come to center and right field. It’s definitely a positive that he’s not leaning out on pitches on the outer half and trying to pull them, but he’ll need to learn how to rip pitches on the inner half to left field if he’s going to be a consistent power threat. Here’s a heat map of his contact in 2013, per Daren Willman’s great MLBFarm site:

Amed Rosario_HeatMap

It seems that most of Rosario’s contact to the left side is on the ground, whereas his line drives and fly balls come to center and right. Per his spray chart, just one of his fifteen extra-base hits went to left field, with nine to center and five to right. Just three of his 34 flyouts were caught by left fielders, as well.

A major part of the problem is Rosario’s tendency to lose his posture during his swing, extending his hands too far and leaning out at the ball. Compare the homer off of Crum with his flyout to the same part of the field in the at-bat immediately preceding it:


In the home run clip, Rosario stays very stable and upright, allowing his hands to rip through the hitting zone and sting the ball. Here, his right shoulder is dipping down all the way through the swing, giving him less explosion through the ball and looping  underneath it. It’s obviously very tough to do anything with inside pitches from this position, and when Rosario dips his shoulder like this, he’s cutting off a lot of the advantages that his quick hands give him. Thankfully, this is very fixable, and Rosario has years to fix it. If he can be more consistent in his posture and cut out the shoulder movement, his bat speed should play more consistently and make him above-average in both contact and power.

Like most young hitters, Rosario will occasionally get overaggressive and pull off the ball:


The funny thing about this swing is that this is roughly what Rosario should do against pitches middle-away on in–stay tall and let the hands rip through the hitting zone. His posture here is much better than in the .gif above. The problem, of course, is that Tim Mayza’s pitch here is a fastball that starts on the outside corner and tails off of it, rendering the pull-oriented path of Rosario’s swing dramatically misguided. Two pitches later, Mayza came inside with a breaking ball and Rosario reverted to his shoulder-dipping ways:


Clearly, there’s a lack of consistency here. Rosario stayed tall on a pitch off the plate away, then leaned out over a pitch inside. As I stated earlier, he’s not a total hacker at the plate, but his pitch recognition skills aren’t all that refined yet, and so he occasionally can have head-scratching sequences like this. Here’s another swinging strike on a breaking pitch, this one a slider from Bluefield righthander Brady Dragmire:


This is a well-located two-strike offering, and Rosario again fails to stay consistent with his mechanics, stepping slightly in the bucket and relying on that shoulder drop to get his bat to the outside corner. He doesn’t use his lower half much here, throwing him out of whack and causing his back foot to fly up after the swing.

In sum, Rosario is a player who already shows a diverse skillset. He has bat speed to burn, and his size and strength give him the potential to provide above-average power for a middle infielder. He’s also fairly polished for a 17-year-old, as evidenced by his ability to demonstrate his tools against much older competition in 2013. On the flip side, there’s a lot for him to work on, but it’s all just a matter of slowing the game down, refining, and gaining consistency rather than innate athletic deficiencies, and he has a lot of time to smooth out those rough edges, to say the least.  He has a long way to go, but his ranking as one of the top short-season prospects is well-deserved, and I expect his raw statistics to improve in 2014 with a year of adjustments and reps under his belt. Rosario should already be a target for deep-league dynasty owners looking to jump on the best of the newest crop of international prospect, and he’s still a player to track for those in shallower prospect formats, as he’s a definite 2014 breakout candidate.

Nathaniel Stoltz is a prospect writer for FanGraphs. A resident of Bowie, MD and University of Maryland graduate student, he frequently views prospects in the Carolina and South Atlantic Leagues. He can be followed on Twitter at @stoltz_baseball.

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9 years ago

This is really great stuff! Rosario types are the most exciting to follow, with so many different outcomes possible. As a Met fan I hope he puts it all together ASAP, but I could easily see a real divisive prospect here…