IMO, Luck, Bridgewater, and Winston are way above 50% so it's worth losing out for them if you're sure they will declare
An important point that doesn't get mentioned... is after one year, if you see certain red flags, what certainty can you have that a QB will not pan out?
I think it is high, like 80+%. So I think a good GM could move on after one year if he can stomach the 10-20% chance of being wrong.
And the reward is getting rid of the 80+% chance you are wasting that second year.