How reliable are Hugo / Nebula awards and nominations?

I believe Reynolds has come within just a few votes of making the list at least once (ie he came in sixth in the initial voting).

I also think delayed release may be a factor in both of those cases- UK authors often have their books delayed by 6 months to a year before being released in the US. So a decent chunk of the voting block may not even have read it in it’s qualifying year of release.