Alexander (shoulder) will begin a rehab assignment with Low-A Rancho Cucamonga on Friday, Bill Plunkett of The Orange County Register reports.
Alexander has been on the injured list since early May due to left shoulder inflammation, but he threw live batting practice last weekend and will now progress to a rehab assignment. The southpaw isn't eligible to return from the 60-day IL until July 5, but he appears on track to be ready by that date.