The Tigers optioned Turnbull to Double-A Erie on Friday.
The 25-year-old reached Double-A for the first time in his career last season and posted a 6.20 ERA in four starts. The Tigers did add Turnbull to the 40-man roster in November, so he potentially could be an option for the MLB bullpen at some point if a need arises, but he carries very little fantasy value at this point.