The more you think about it, the more it makes sense.
Ever since the news broke that Seth Jones would be testing free agency, the Blackhawks were one of the teams that were in on the big, right-handed defenseman from the start. Nothing concrete has happened yet between Jones and any team, that we know of, but that's for a few reasons.
Most importantly, for the Blue Jackets to be able to trade Jones, they have to find a team that Jones will sign a contract extension with. Any team that acquires Jones will want to have the assurance that he'll remain with them long-term, rather than leaving them in a year when he's a free agent.
It's tough to say that there's a team that has a better reason to convince Jones to sign an extension than the Blackhawks, who dealt veteran defenseman Duncan Keith to the Edmonton Oilers on Tuesday in exchange for Caleb Jones and a conditional third-round pick. Caleb is Seth's younger brother. The two are close with each other, and the idea of playing in the NHL on the same team as your brother must be a compelling one.
There's a history between the two teams, too, as Mark Scheig pointed out above. They've made big deals around the time of the draft before. Three days after the 2015 draft, the Blue Jackets acquired Brandon Saad, Michael Paliotta, and Alex Broadhurst in exchange for Artem Anisimov, Jeremy Morin, Corey Tropp, Marko Dano, and a 2016 fourth-rounder. Then, in 2017, the Blue Jackets made waves with the acquisitions of Artemi Panarin, Tyler Motte, and a sixth-rounder for Saad, Anton Forsberg and a 2018 fifth-rounder. That trade took place on draft day. Both of those trades saw players and draft picks moved.
The Blue Jackets have a surplus of first-round picks, and a number-one defenseman who is ready to move elsewhere. The Blackhawks have young talent (Kirby Dach, Connor Murphy, Adam Boqvist) and Seth's younger brother.
It's a match made in heaven.