The Twins had two fairly prominent signings:
They are both 16 years old, so there's no point in expecting anything immediate out of either.
That's the general rule with the non-draft signings. They are typically very young and very raw.
Ynoa has an interesting background. His brother Michael holds the record for largest bonus given an undrafted free agent; Michael Ynoa hasn't come close to the majors yet, but the Oakland A's put him on their 40-man roster to keep him from getting snatched up in the Rule 5 draft. He has, for the second straight season, an ERA above 7.5 in high A ball.
We can guess the Twins hope little brother can do better than that.