The Twins ruin prospects two ways They promote them too slowly and the player stagnates OR they rush them too quickly and the player is overwhelmed. No matter how the Twins promote prospects they are always clearly wrong in hindsight.
I wonder the reason for the move. I don't think they lack confidence that Terry Ryan can make a decent deadline trade. I think they lack confidence that he will make enough trades (fire sale).
I think the more relevant question for Blankenhorn is whether he can handle 2B. There were questions whether he could stick at 3B. At 1B or LF he will have to really hit to impress.
At some point it will be too late to trade Santana. His effectiveness will decline with age. This is similar to Josh Willingham. Trade him now before he's untradeable. This is a seller's market and the Twins have an asset that multiple teams want.
A 50-100 prospect who pitches plus some sweetener like a decent international bonus slot or an A-ball reliever with a live fastball would probably get me to bite. I think the Twins will have the luxury of multiple bidders driving up the price on Ervin Santana. They could do very well.
I hope the Twins keep Nunez to mentor Sano and Polanco. I doubt they get much in return for trading him since he will be a pending free agent next season.
Plouffe, Dozier, Santana and Park or Arcia. These are the only guys who will bring back the pieces they need (catcher, more pitching depth) and there are replacements for all of them on the roster.