Miami needs his contract for big trades. He needs to improve his value, whether to stay or leave. Many Miami Heat fans assumed that Duncan Robinson would get traded this off-season — either in a big deal for Kevin Durant or Donovan Mitchell or a smaller trade for a starting power forward. We’re now in August, and no trade has materialized. Miami may go into the season with Robinson on the roster. And what does that look like? Will he remain out of the rotation? Max Strus took his starting role late in the regular season, and then Victor Oladipo…