I don't see it as unreasonable to think that Frelick could come up and exceed the .274 OBP Taylor is giving, or provide a threat to reach second base that Davis doesn't bring. He has hit immediately (or close enough to it) at every level. The downside risk is minimal, given the output there is limited to Taylor running into one once every couple of weeks.
Contrast with Turang, who has taken some time to get going at every level. Understandable, given he's been young for every level. They may be preparing him for a call-up (given the starts at 2B and 3B), but expecting offense is a mistake. He's best suited to be on the opening day roster next year with patience through any early struggles. Unless Peterson is lost for the season, I'd wait on Turang.