Arano was placed on the 10-day disabled list Monday with a mild right rotator cuff strain, Meghan Montemurro of The Athletic Philadelphia reports.
It's unclear when exactly Arano picked up the injury or how long it will keep him sidelined at this point. He underwent an MRI on Monday and is expected to take the next few days off from throwing before being reevaluated when the team heads to Washington, D.C. later in the week. The 23-year-old has been rock solid in a relief role this season, allowing just one run while striking out 13 batters through 12 innings of work. Zach Eflin, who is scheduled to start Tuesday, was recalled from Triple-A Lehigh Valley in a corresponding roster move.