That's not how crowd sourcing works. With large enough crowds, your crazy people at one end counteract your crazy people at another end. That's why using crowd sourcing to predict the amount of jellybeans in a container works.
If you use just the top 20%, then you get all the crazy people. That doesn't help any. What does help is finding a factor to predict how much the crowdsourced guess is wrong by in order to counteract bias.
I'm saying crowd-sourcing is a poor method for predicting contracts because the player doesn't take the most middle of the pack offer. He takes the highest.
It doesn't really matter what is the average of what all 30 GMs think Davis should get paid or would be willing to pay him. It only matters what the one guy who thinks he should get paid the most thinks he should get paid.
The higher end is more likely to be accurate in this sort of thing. Crowd sourcing is good for when there is an expected range that a result could fall in. That's not really the case with free agent contracts.