Seattle looks like a team that can do something

Ritchie being traded provides the Leafs with a lot of cap space and they can get Holl out for a cheaper dman.

Twarynski is more of a sweetener to make up for the Leafs loosing a left wing, neither player hurts the leafs cap too much

Seattle's goalie situation is currently looking worse than Arizona as the Coyotes can actually score on it, so anything can be an improvement, especially Gibson. With a younger team, the Ducks need to loose some of the old guys, though their leadership is good for the younger guys, you don't need too many. Carrick adds to Seattle's depth and opens space for the Ducks to fit another young player to develop.

Ducks get a young player to replace Carrick and a young(ish) goalie to replace Gibson, both are also super cheap and fit the young ducklings on the up

Tarasenko can become the star for Seattle bringing real first line goal scoring.

Blues get Donskoi to make up on the right wing, letting Buchnevich play a more important role. Soucy adds a bit more to the left defense. Fleury can be sent to the minors and be a useful piece in the future

Koskinen isn't really going to be used outside of like 2 test games to see if he turns into Ken Dryden overnight, so he's just going to the minors and all thats really gained is cap space and a draft pick.

Grubauer is being sent of in hopes that the Oilers jersey will make him a vezina candidate again and solidify the back end. Also they can say they no longer have Koskinen