Weird deal unless Vancouver retains.
The Senators have 4.5M of dead money sitting in the minors doing absolutely nothing for them, and that's going to continue into next season. They're going to want to clear that off the books, but they are no longer in a position where giving up futures to dump him makes any sense.
I have to assume that Vancouver's plan is to make this swap, pick up an asset and then buy Zaitsev out this summer. There is basically no change in Myers cap hit if he's bought out [6M vs 5.33M] but Zaitsev drops from 4.5M to 2.83M. Going from 6M down to 2.83M opens up a decent chuck of cap space for them. If they have to retain it probably gets too thin for it to be worth their while.
I think there is still a perception that Tyler Myers is a good player. I don't believe he is, but perception is reality in these cases. Every time a GM looks at him he's 6'8", y'know? That goes a long way in the NHL. He would clearly be the more desirable piece among the two.
The Senators probably have no idea who will play RD for them next season. Zub is a UFA. Hamonic is both a UFA and not very good. They've clearly closed the book on Zaitsev. Surely they can't be penciling in Lassi Thomson. They kind of need some bodies.