If they opt to prioritize keeping the maximum amount of pitching talent in the organization, they could set up the staff like this:
Alzolay, Adbert
Arrieta, Jake
Davies, Zach
Hendricks, Kyle
Williams, Trevor
Chafin, Andrew
Kimbrel, Craig
Maples, Dillon
Mills, Alec
Tepera, Ryan
Winkler, Dan
Workman, Brandon
Miller, Shelby
Last spot (Adam, Jason; Holder, Jonathan; Ryan, Kyle; Stewart, Kohl; Wieck, Brad)
That keeps Maples and Miller in the organization. All of the listed candidates for the last spot have options remaining, so that could be your Iowa shuttle.
Neither Ryan nor Wieck have pitched in a game yet. Seems like they may start off with only one lefty in the bullpen.