Thought Sanders won this back in March?
He did - in the caucuses. This primary means nothing to the democrats - they are strictly caucus. (A “beauty poll” - like what the Republicans used to use in Colorado).
The Republican primary in WA does matter - with the winner getting the caucus delegates bound to them on the first vote. So while Cruz supporters got 40/41 of the delegates voted on at the convention - they will need to vote for Mr. Trump on the first ballot.
The state of Washington has a caucus and primary on the Democratic side. The primary is just a beauty contest, no delegates are awarded by it. Though it is a propaganda victory, as Clinton can claim she won Washington when over 600,000+ people voted, as opposed to Sanders winning in March when like 200,000 Democrats voted.
This was really just a beauty contest.
He did, big time.