Perhaps they figured they didn't need Cruz vs the White Sox (correct), and they were postponing his activation until they did this little starting pitcher dance with Pineda and Smeltzer? Although some might say we could have used him vs Milwaukee...
Assuming they send down Smeltzer and activate Cruz before the Tampa series, that lets them keep Arraez, Astudillo, and all the current relievers on the roster too, until Garver or Pineda is ready to come back.
Garver sounds like he'll be ready to play for the weekend, Rocco says Pineda is only going to miss 1 start and Cruz might be ready to go for Tampa. So it'll probably be Smeltzer getting sent down after his start -> Garver being activated and possibly Arraez getting sent down after today's game -> Cruz being activated. When Pineda gets activated its probably going to be either Littel or Astudillo being sent down.