Ideally, they'd lock up all of Berrios, Buxton, Sano, Kepler, and Rosario. Realistically, I think the majority are going to want to test the market. I think the most appealing balance between cost and upside is Buxton. He's had enough struggles so far to give the FO some leverage, though he has performed well enough to certainly justify at least talking about an extension. I don't know, maybe that second fact is enough for him to want to reach free agency as quickly as possible. In any case, I doubt they'll be able to lock up all of them, given the increasing rarity of pre-arb extensions. If it was my choice, I'd prioritize Buxton.