Guardians Hot Stove: Who is Alfonsin Rosario?

Guardians hope to cash in on young lottery ticket

In one of their few offseason moves, the Cleveland Guardians traded reliever Eli Morgan to the Cubs in exchange for 20 year-old outfield prospect Alfonsin Rosario.

Morgan was a staple to the Guardians bullpen over the previous three seasons, and despite never having velocity capable of overpowering a hitter, Morgan found his way into becoming a capable middle reliever for the Guards, especially upon his recall from Triple-A Columbus in 2024.

High leverage was never the name of the game for Morgan, but the Cubs were mostly seeking someone capable of getting outs effectively out of the bullpen. Morgan provides that along with a plus changeup.

It didn’t come at the cheapest price for the Cubs, however, as they gave up their 21st ranked prospect, per MLB Pipeline, Alfonsin Rosario.

Rosario is 20 years old and stands at 6-foot-1, 210 pounds out of the Dominican Republic, and bats and throws right-handed dominant. Rosario, the younger brother of former Padres top prospect Eguy Rosario, was a sixth round pick of the Cubs in 2023 and is the definition of a toolsy prospect, the kind in which we’ve seen the Guardians struggle to develop in recent years.

Rosario has plus speed, was clocked throwing over 100 miles per hour at the Perfect Game Showcase in 2022, is a capable fielder in the corner outfield, and his bat speed translates to a power tool that is lauded as a plus tool, turning in exit velocities comfortably over 105 mph.

He powered out 16 home runs and stole 20 bases in 2024 for Chicago’s Single-A Myrtle Beach, but he also struck out 32.3% of the time. Rosario does possess a good enough eye, but his overall chase rate and pitch recognition are things he must improve upon within the Guardians system in order to rise and develop. That being said, what’s there so far is encouraging, as is his improvement that he showed off in his 2024 that showed his 2023 struggles in Rookie ball were just him merely getting acclimated.

Rosario is a “lottery ticket” type of prospect. A lottery ticket is just that, though, and we’ve seen players like this before within Cleveland’s system (Gabriel Arias, Jhonkensy Noel, etc), but with an organizational shift towards patience, improving approach and chasing less, and pulling flyballs and line drives, Rosario will fit in much better now than he would have just a few years ago.

As exciting as it is to see what Rosario can do within this system, it’s equally enticing seeing Cleveland’s front office turn to a place of tremendous depth and deal a solid but not spectacular reliever who had also proved he was just as capable of being sent down as he was churning out a month’s hot streak for a young, toolsy prospect, whose potential is a quantifiable value to the future of this team.