Mellman was the only one to get Reid's victory right in 2010.
This isn't Nevada though. Nor is it 2010. Citing one right answer doesn't make them automatically more reliable than all of the other reliable pollsters that put Gardner ahead.
FWIW, Mellman got Heitkamp's win right as well.
Mellman was also the only pollster to call Shelley Berkeley's win.
What were Mellman's results for NV? Even if they had Berkley winning by 1 point, they were closer to the end result than the other pollsters which had Heller up 3-5 points.
As the link showed, the poll that Berkeley chose to release had her up by 3 points, which was further from the actual result than PPP or Marist were (albeit barely closer than SurveyUSA)