I'm damned intrigued by McKay too. He was the "John Olerud Two-Way Player of the Year" in his freshman and sophomore years, and is a lock to win it again this year. Prior year stats on his bio page:
http://www.gocards.com/roster.aspx?rp_id=6788&path=baseball
If the Twins take one of the two-way guys I really hope they find a way to develop him as such.
I think each player would face different challenges in doing that however.
With Greene, playing on the left side of the infield everyday would involve a lot of throwing. Too much I would think, to simultanously pitch either as a starter or reliever. He would have to move to first, DH, or maybe the outfield to keep his arm in shape. But to do that he'd have to hit like a corner bat.
With McKay, since he's already planted at first base he wouldn't throw basically ever during everyday play, no position change would be needed. The downside obviously is he would have to mash to hold an everyday job at first.
So, to remain two way players, both guys would have to mash.
Question- which player has the higher upside with the bat? Higher floor?