I think Carolina did well with their situation.
Stankoven is going to be a first line winger. They also got two firsts and two thirds. They started out with Necas and turned that into Stankoven, 2 1's and 2 3's. They also in the meantime got one of the league's better forwards to play for them during that span. I guess they gave up Drury and a 2nd also, but to me getting basically the equivalent of Stankoven, a 1, and a 2 is a good deal for Necas.
I don't really get why Rantanen's family didn't like Carolina. I would totally get it if he was turned off by that dreadful dressing room or how cheap the owner is, but his family didn't like Carolina but likes Dallas? Seems pretty similar to me for what Rantanen, a foreigner to the USA, would likely believe ("Southern USA and all the cliches that come with that").
I should say though that I have no problem with Rantanen not wanting to sign with Carolina, even if I don't totally get the sequence of events. He was a UFA. No one should've expected he'd sign with a random team he was traded to. If he wanted to call the shots and only field offers from four teams, who can blame him? He was a UFA in July, and could've done that in July, so either meet his demands now or he was waiting until July.