In a perfect world, I'd like to see Chapman go to the rotation next year and Arroyo dealt and Bailey/Leake at the backend of the rotation. Arroyo is having a pretty nice season. A bounceback one in which none of us expected I think, but he's getting paid too much for what he provides. A team needing pitching (if he'd accept the trade) may be willing to take him on a 1 year deal after this season. Walt seems to be high on Arroyo though so that may not be an option. Leake has essentially provided the exact same production this year as Arroyo (if looking at WAR) and costs a lot less.
One possible option...what about trading both Bailey and Leake for a pitcher that is an upgrade who may be under control for a few years to shore up the rotation? You could plug Chapman in and let Arroyo play out his contract and then let Corcino or Cingrani step in after next season.