I'd put him 3, behind Sano and Buxton. The reason being is he is a pitcher with #1 stuff and I rank pitching slightly above position players. My guess is he will have the 3rd highest ranking maybe 4th in most top 100 list when it comes to Twins related prospects. I like Hicks and Arcia I just don't know where they'll be ranked in most top 100 list because they have been around a while, and many list are heavy with players in the past 2-3 years.
Updating this for the May trade. He has upside like Meyer (a little less) but far more question marks so I rank him in the Berrios/Kepler tier giving the Twins an awesome top ten. I'm not sure if Willingham or Morneau will also get traded this offseason but this system is becoming great.