Turnbull is expected to claim the final spot in the Tigers' Opening Day rotation, Evan Woodbury of MLive.com reports.
Manager Ron Gardenhire hasn't officially named Turnbull as the fifth starter over Daniel Norris, but the Tigers appear inclined to use the latter out of the bullpen to give the team another reliable setup arm while Drew VerHagen (forearm) opens the season on the injured list. Even if the injuries to VerHagen and Michael Fulmer (elbow) hadn't intervened, Turnbull would have been a justifiable pick for the rotation after allowing just three runs and posting a 15:2 K:BB in 15 spring innings.