Yes, we're only two games into the preseason, but I assert that the Jackets' blueline was set weeks ago. Here's my reasoning.

Jack Johnson was signed, in my opinion, to be a mentor and swap time with Jake Christiansen on the third pair, opposite Erik Gudbranson. With Werenski and Severson on the first pair, Provorov and (probably) Jiricek on the second pair and Mateychuk getting professional experience in Cleveland and first call up, this made sense.

Then Waddell traded Laine for Harris (essentially). Suddenly, the plan had a monkey wrench taken to it. Unless Jiricek joins Mateychuk in Cleveland with Harris on the second pair (not beyond the realm of possibility, but unlikely), changes to the plan have to be made. Werenski, Severson, Provorov and Gudbranson are fixed. IMO Jiricek got boned, last year. Maybe he did need to spend time in Cleveland. Fine, don't tell him to get an apartment. This year, unless he totally effs up, he's a lock on the second pair. Which leaves Harris, Christiansen, Johnson and Mateychuk competing for the opening on the third pair and 7th D spots. Mateychuk automatically loses that competition. I don't care how great he is in preseason, he's going to Cleveland because he's the only one of the three who doesn't need to clear waivers to go to Cleveland. Johnson's roster spot is secure. He'd never clear waivers and, if by some chance he did, he'd almost certainly refuse to report. That leaves Harris and Christiansen. Harris has played for Montreal for three years while Christiansen has been in Cleveland with a couple cups of coffee in Columbus. It's not hard to figure out who has the advantage there. And I assert that Waddell didn't obtain Harris to be the 7th D.

So, as soon as Harris joined the team, the blueline was set.

Werenski - Severson

Provorov - Jiricek

Harris - Gudbranson 

J. Johnson