I don't now why everyone is bringing up this whole "sign-ability difficulty" thing. From Chayka's quote it was pretty clear that they didn't want to sign him.
His worth a lot more in a trade signed to an ELC, than unsigned. We can bet that Yotes, and the other team that drafted him would have preferred to sign him, regardless if they intend to trade or not.
The only circumstances I could foresee of a club not wanting to sign a player is due to the 50 and 90 player maximums.
Any way, trading a 3rd round pick (and unprotected?) for the rights to negotiate and sign a prospect that never played professional hockey seems high to me. Particularly when considering that two teams failed to sign him prior.