Signed for just $7,500 in 2015, the 21-year-old Guerrero made it out of complex ball for the first time in 2018. After pitching in a closer’s role (if there is such thing in Rookie ball) and racking up six saves for AZL Cubs 1, the hard-throwing righty was promoted to Short-Season Eugene at the end of the season.
Short and stocky, Guerrero is a muscular 5-foot-11 and 180 pounds. A relief-only prospect, he throws exclusively from the stretch and comes right at hitters with the heater. His lively fastball sits in the mid-90s, peaking at 96 mph in my look. He didn’t walk many hitters this year, but low-minors stats often don’t paint the full picture: Guerrero’s control and command grade out at 30/40, meaning he’s a thrower needs to iron out aspects of his pitchability. A hard slider at 84-to-86 mph is the primary off-speed, showing the signs of at least a future playable pitch with tight spin and consistent short tilt. He mixes a softer curveball and infrequent change, wrinkling both pitches in more often to lefties.
Guerrero is a marginal prospect, likely more of a FV 30 type (Organizational Depth/4A Ceiling) for now than one who projects to hold down a consistent roster spot in the big leagues. He’s likely to reach full-season ball for the first time in 2019, his fifth year with the Cubs.