Harrison (back) is expected to throw a bullpen session in Toronto this weekend before making another rehab start, Jeff Wilson of the Fort Worth Star-Telegram reports. The plan is said to be tentative, but Harrison struggled again in a rehab outing with Double-A Frisco on Wednesday (five earned runs in six innings) and it sounds like the Rangers want to see more before entrusting him with a major league rotation spot. Harrison, who underwent spinal fusion surgery last summer, has made just four starts in the majors since 2012.