The Injured List (formerly Disabled List) lets clubs move an injured player off the 26-man active roster and call up a replacement. Three tiers exist by minimum stay.
10-Day IL: position players and catchers, minimum 10 days. 15-Day IL: pitchers (starters and relievers) — extended from 10 to 15 in 2022 to discourage skipping a start with a minor injury.
60-Day IL: severe injuries. Players on it are removed from the 40-man roster, opening space to add new 40-man players. Tommy John surgery cases typically land here.
Kodai Senga's 2024 shoulder issue moved to the 60-day IL for an extended absence; Yusei Kikuchi shuttled between the 15-day IL and rehab outings. Early-season IL moves are critical to track for Japanese players.
→ Related: 26-man roster / 40-man roster / Rehab assignments