Born: January 30, 1993
Height: 6’0″
Weight: 182
Bats: Right
Throws: Right
Signed: Int’l Free Agent, 2011
Country: Dominican Republic


Rosario was 19 when he signed, which is late for a Dominican prospect.  He threw in the low-90s originally, but sometime in either 2015 or 2016 he dropped down to a sidearm motion.  His velocity was less after that, as he topped out around 90 and mostly threw in the upper-80s or even lower, but he became much more effective.  He throws from a low crouch and lunges toward the plate, which may make his pitches harder to pick up.  Despite the sidearm motion, he’s a flyball pitcher.

DSL:  0-0-0, 2.70 ERA, 0.90 WHIP, 6.2 IP, 2.7 BB/9, 8.1 K/9

Rosario got into just three games after signing.

R:  1-1-0, 3.61 ERA, 1.37 WHIP, 42.1 IP, 2.8 BB/9, 7.0 K/9

The Pirates moved Rosario up to the GCL despite his having almost no pro experience, so they probably see at least a little potential in him.  He pitched decently there, especially considering his lack of experience.  He started five games and relieved in ten.  He had some trouble with longballs, allowing five, and with left-handed batters, who hit .318 against him.  He was a strong groundball pitcher.  The ERA is a little misleading, as 12 of the 29 runs Rosario allowed were unearned.

A-:  2-2-1, 3.27 ERA, 1.18 WHIP, 44.0 IP, 3.9 BB/9, 9.4 K/9
A:  0-1-0, 6.14 ERA, 1.50 WHIP, 7.1 IP, 4.9 BB/9, 7.4 K/9

Rosario opened the 2014 season in extended spring training, then spent the month of May at West Virginia, where he struggled a little.  The Pirates moved him to Jamestown when the NYPL season started and he pitched well in relief there, with a slightly high walk rate but very good K rate.  Overall, he held both left- and right-handed batters to an OPS below .590.

A:  2-0-0, 1.75 ERA, 1.17 WHIP, 25.2 IP, 3.2 BB/9, 7.4 K/9
A+:  3-3-3, 2.92 ERA, 1.20 WHIP, 49.1 IP, 2.6 BB/9, 10.2 K/9

Rosario went back to West Virginia and made nine appearances, including two starts.  He pitched well enough that the Pirates promoted him to Bradenton, where he spent the rest of the season in the bullpen.  He continued to pitch well there, with very good walk and K rates.  He had only a mild platoon split.

A+:  1-1-0, 2.64 ERA, 1.21 WHIP, 30.2 IP, 3.2 BB/9, 7.6 K/9
AA:  2-2-0, 1.87 ERA, 0.95 WHIP, 33.2 IP, 3.5 BB/9, 7.8 K/9

The Pirates sent Rosario back to Bradenton to start the year.  He continued to pitch well, although with a below-average K rate.  In mid-June, they promoted him to Altoona and he put up nearly identical numbers except that his BABIP dropped from .296 to an unsustainable .209.  His xFIP, which was 3.88 at Bradenton and 3.95 at Altoona, was probably a good measure of his performance.  On the year he had only a slight platoon split, with a .528 opponents’ OPS by right-handed batters and .554 by left-handed.

A+:  0-1-0, 4.85 ERA, 1.62 WHIP, 13.0 IP, 7.6 BB/9, 8.3 K/9
AA:  3-1-3, 1.80 ERA, 1.58 WHIP, 45.0 IP, 7.0 BB/9, 8.6 K/9

Rosario had a strange season.  He opened at Altoona and maintained a low ERA, but control problems mounted until he walked 16 batters in 7.2 IP in July.  The advanced metrics weren’t buying the ERA, as Rosario had an xFIP at Altoona of 5.31.  The Pirates sent him down to Bradenton for the month of August and he tried raising his arm slot back closer to overhand, but it didn’t work as the walks continued.

Rosario had a good run of ERAs that weren’t supported by his other numbers, but that may have come to an end with the control problems.  He’ll be a free agent after the 2018 season.

2018: Minor league contract
Signing Bonus: N/A
MiLB Debut: 2012
MLB Debut: N/A
MiLB FA Eligible: 2018
MLB FA Eligible: N/A
Rule 5 Eligible: Eligible
Added to 40-Man: N/A
Options Remaining: 3
MLB Service Time: 0.000
December 11, 2011: Signed as an international free agent by the Pittsburgh Pirates.