Any announcement of who gets sent down? I wouldn't be surprised if it is HobieCat. I think Abbott stays and is still a 5th starter candidate when Irvin is sent back down.
The other way to play it is sort of to stream guys into the 5th slot or bullpen help. Send down Abbott, call up Irvin, send down Irvin, bring up a bullpen arm, send the arm (or Machado) back down and call up Espino for the next start, then bring in another bullpen piece to be sent down for Abbott or someone else for a start. Gives the team an extra bullpen arm most of the time. Could even build in a Ward start at some point.