It's always about other guys when you're talking about a redraft, and it was you who brought up the redraft. Brannstrom wasn't doing anything that special, he just wasn't not living up to expectations. Vilardi had spent 2 years mostly injured, Lias Andersson was faltering, Mittelstadt and Rasmussen were doing nothing special in th NHL, Brannstrom was doing well, but not better than expected.
There's no way that that trade is made without some sort of discussion between Vegas and Stone about his willingness to sign and the preliminaries of a deal. Players like Brannstrom are not traded for rentals anymore and really haven't been since the cap era began. Hossa, Kovalchuk, Hall, whomever you want to name as a big rental acquisition.
That does not matter. The value of a high 1st round pick is not only the possibility of selecting a superstar player but that you get that player on a mandatory 3 year entry-level contract which is now quite close to league minimum. If this player is even an average NHLer for 2 of those 3 years that represents a gigantic savings, plus the opportunity to sign this player to a favorable long-term contract. Fiala's cheap days are done. In his first 6 years in the league, he made $14M, he will make that over his next 2 years. He no longer represents a large potential cap savings. He's worth less than a 6th overall pick, not significantly less, but certainly less - Minnesota would need to add to that deal.
Anchoring bias is very real and once you hear the idea of Fiala for Devils 1st round pick from a trusted source it might make more sense. It's not a fair deal.