Just like Jordan Zimmermann was a #2-3? I disagree. A better changeup could make him a good #2, nice to slide in at 3, IMO.
Zimmermann is still only a 2. A very good two. He's not an ace. He needs to become more dominant at finishing guys off. He's still improving and could get there, as soon as next year, but he's not a true #1 just yet.
Peacock is a guy Im hoping finds his way into the rotation next year, but he's not a sure thing and his ceiling definitely isn't as high as Zimmermann's. 3 at best, most likely a 4/5. While he is still relatively young, its unlikely the change up comes far enough to be a consistent enough pitch for him to be a frontline guy. He can be included in a deal to upgrade the team somewhere else.
As far as Span ... Id go Coffey, Milone, and Desmond if that is enough to entice Minnesota. Milone seems to be their type of pitcher and could do well in that yard. He could possibly even help their pen this year down the stretch if they wanted to give him a shot.