I disagree strongly. I think if anything, you've got it backwards. There's little risk in rolling with Carr. He's coming off a solid rookie year. By rolling with him, if he fails, the GM didn't draft him so the blame on that failure won't fall on him. And he'll have the opportunity to build up the team around the QB for his guy if Carr fails.
If he drafts Winston and trades Carr, he takes the risk that Winston will fail and the blowback falls on him...plus if Carr succeeds, he looks even worse. And the Raiders still lack talent in so many key areas.
320 is not that much of a difference. You look at a lot of the first round trades of late, it fluctuates greatly.
As for the site, from what I recall, he altered the chart based on the trades to values that better reflected the values at that point in time.
Why would the Raiders move down? Think about who they're going after. Likely a pass rusher or a WR. Two of the deepest positions in the draft. By moving down, they don't sacrifice that much. They'll have the opportunity to draft a pass rusher like Shane Ray, Dante Fowler Jr., Bud Dupree, Vic Beasley, or Nate Orchard. If they go WR, they have a shot at Kevin White, DeVante Parker, or DGB. The Raiders needs match up well to the strengths of the draft.
Think of the Rams in 2012. That was also true. The Raiders are in a good position to move down into the mid first.
It's easy to poo-poo on trades with how hard they are to predict but I don't think this is an unrealistic scenario.
Fisher never has shied away from immature players at other positions. From what I recall, Fisher didn't want Young. I have a hard time believing he wouldn't want Winston. Seems like his type of player to me.
I'd take the risk. But I don't blame you for not wanting to. The one big thing for me is if I found out the rape allegation was true, I wouldn't draft him.