IMO the weakest point in AZ roster is LF/ DH which could use some help. Larnach is a very capable LH LFer & DH, where last season Larnach was well-established. (LH) Emmanuel Rodriguez is close to make that jump & Jenkins is not far behind which makes Larnach dispensible. (LH) Keirsey needs to be established at the MLB level & not rot at AAA. He & (BH) Castro are more than able to hold down the position until Rodriguez is ready. Vazquez will be gone after this season, I can't see MN affording Jeffers extension so he's gone a year after that. After them, MN has no depth. So Del Castillo would fill that need. MN doesn't really need Nelson, he's thrown in to balance the trade.