I'm not sure I take Voracek and a 1st for Tarasenko (at 50% retained) if I'm Seattle. I think that they could get more out of eating that much cap space, but maybe they are higher on Voracek than I am. Let's say they retain $2.75M of Tarasenko's $7.5M cap hit in that trade. That means that they are eating up $11M of their cap space for the next 2 years AND using 1 of their 3 salary retention slots in order to acquire Voracek and the 13 overall in a draft that is viewed somewhere in between "weak" and "total crapshoot due to COVID severely limiting scouting opportunities." That seems like a poor way to allocate $11M of cap space even before you consider that this deal also eats up their expansion draft selection from us.
Again, I might just have too low of an opinion on Voracek, but I just don't see him as being worth anything close to his $8.25M at this point. He turns 32 in a month and I don't think the 66 point pace player he has been for the last 3 years is going to continue when he isn't playing the large majority of his minutes with Giroux and Couts. I think he can be a 65 point guy with a legit top 20 center, but is Seattle going to get one of those? If not, who is he on their top line? A 55 point guy? If you're spending $11M on that 55 point guy (plus the 1st rounder), what would you say you're overpaying by? $5M? So is "overpaying" by $5M in back to back seasons really worth a single 1st round pick in a weird draft? In a flat cap league, I think you can get yourself more assets for eating $10M of total bad money.
If I'm Seattle, I think I'd rather just keep Tarasenko at $7.5M per, play him like a star player and hope that he returns to form. 2 year risk instead of 3, it costs me $7.5M against the cap instead of $11M for those 2 years and if he returns to being a 30 goal guy I can get a better return either at the trade deadline or next summer (or just keep him because he has become a franchise player).