It is a tough one since the #1 thing holding the Twins back is something that resembles an ace. Gray doesn't have the K's that you ideally want but he is an ace-lite. That refers to the next tier of pitchers behind the obvious aces like Kershaw, Greinke, Felix, Sale, etc... The part that puts him into the ace-lite category is that he gets a lot of GB's which limit big innings. I really, really like Berrios and think he could become as good as or better than Gray but it is really common for elite prospects (better than Berrios) to come up and struggle. Some never figure it out and some take a couple of years to figure it out. I think I would do the trade and take the sure thing. If we could swap in a slightly lesser prospect for Kepler I would feel better. These are two of my favorite prospects right now.