In Week 4 of the 2026 MLB season, several key hitters are dealing with injuries that could affect fantasy baseball lineups. Corbin Carroll, the right fielder for the Arizona Diamondbacks, is day-to-day due to a lingering back injury. Ronald Acuña Jr. of the Atlanta Braves was hit in the wrist but has negative X-rays and is also day-to-day. Adley Rutschman, catcher for the Baltimore Orioles, is currently on the 10-Day Injured List due to a new ankle injury and is expected to return next week. Other notable players include Juan Soto of the New York Mets, who is recovering from a calf strain and aims to return by the end of the week, and Mookie Betts of the Los Angeles Dodgers, who is targeting a return this weekend. Players like Royce Lewis are set to return soon, while others like Jonathan India and Jackson Chourio face longer recovery times. Fantasy managers should monitor these situations closely as the season progresses.