Sims (elbow) threw 10 fastballs off a mound Wednesday, C. Trent Rosecrans of The Athletic reports.
Rosecrans notes that Sims took part in a modified flat-ground bullpen session called a "short box" drill, which features a catcher on the plate or slightly in front of it. That activity could be the final step before Sims resumes pitching traditional bullpen sessions. Once he completes a few bullpen sessions, Sims will advance to facing hitters in live batting practice or simulated games before he receives clearance to make his spring debut. The 26-year-old still looks to have a good chance at being ready to go for Opening Day.