According to Joe Frisaro of MLB.com, the Marlins are considering adding a third baseman via trade. Targeting Olt makes sense, because he can easily move to 1B when Colin Moran is ready to come up next year and take over 3B. The club will only give up its young pitching if it returns "a big league prospect under club control."
We have done business with the Marlins already, trading Bogusevic for Ruggiano. That could be the precursor to a bigger deal. We traded need for need; now it's time to step up... Heaney (#2) or Nicolino (#3) would be reasonable pitching prospects in a deal for Olt (#5), especially when the FO has stated that Kris Bryant is sticking at 3B.
Garrett Jones has a high potential to be a bust for the Marlins, so Olt makes more sense than Middlebrooks. If we want to keep Olt, maybe sending a versatile player like Luis Valbuena to play 3B as a stopgap could net us a potential closer like Caminero (#20) if we threw in some cash.