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Scouting Report
Updated May 19, 2026
Luis Castillo (note: sources reference Luis Castillo, not Diego Castillo) is experiencing a difficult 2026 season with the Seattle Mariners. After posting a 6.29 ERA and 1.66 WHIP over 34.1 innings in his first seven starts, the Mariners are considering removing him from the rotation when Bryce Miller returns from injury. Castillo has allowed at least four runs in six of his last seven starts and has been moved to a piggyback/bulk reliever role. His spot in the starting rotation is tenuous, with the team exploring options including a six-man rotation, bullpen role, or potential demotion. Despite his struggles, the team is proceeding cautiously given his track record as a three-time All-Star and his inability to pitch in relief at the major-league level previously.
Strengths
- + Three-time All-Star with proven track record
- + Showed improved fastball velocity (mid-to-high 90s) in recent outing vs. Royals
- + Struck out six batters in White Sox game despite poor efficiency
- + Has overcome significant struggles before (2021 season)
- + Still capable of quality stuff when healthy
Weaknesses
- - 6.57 ERA through eight starts (one of worst in MLB)
- - 1.66 WHIP indicating high baserunners allowed
- - Allowed at least four runs in six of last seven starts
- - Declining velocity as innings progress
- - Poor pitch efficiency (108 pitches through 5.2 innings in recent start)
- - Allowed two two-run homers in White Sox game
- - Failed to pitch three innings in multiple recent starts
- - 0-4 record with 7.79 ERA since opening day shutout
- - Mariners 1-6 in games he's started since first outing
About
Diego Castillo is a shortstop for the Chicago Cubs.
Player Overview
SS
Chicago Cubs