What value Sandy has is debatable.
The Marlins got great value in the Trevor Rogers trade, getting Norby & Stowers.
They didn’t get much, as of now, for Jesus Luzardo, getting 2 low level prospects Starlyn Caba & Emaarion Boyd.
There were health concerns for both Rogers & Luzardo. Sandy seems to have moved past that and has had a solid June. This increases his value.
He is due much more than Rogers & Luzardo over the next 2 seasons. This decreases value, compared to Rogers & Luzardo, though his contract certainly isn’t a deal breaker for a potential large revenue team looking to add a proven starter on the upswing.
IMO, a team has to make the Marlins an offer they can’t refuse. Would not trade Sandy for a Luzardo type package.