Well, again, as an impartial party, Blackwood's track record is much shorter, he's having issues with his team apparently, and he's recovering from an injury, so I don't know if he has much value.
Gibson's contract, NTC, and performance the last few years likely has him in the same boat though. Not sure what's happened to him, he was really good a few years ago. Teams might try Gibson out because he used to be so good. They might want to try out Blackwood because at one time he was considered a very good "goalie of the future", and his contract is easy to trade for on a "let's try him out and see" basis, where Gibson is the guy, whether he rebounds or not.
Both seem like their value is pretty low to be honest.