Because both of those iHeart stations have no local sound to them. Movin' isn't the best at it either, but they sound more local than Kiss and KUBE combined.
That's in overall numbers, drill down to specific demos and the race is a little closer.
Ask yourself what happened to KPLZ since last summer.
Movin' wins because they are smart and the iHeart stations continue to be iHeart stations.
Kiss spent almost a year doing a better job of recognition and endorsing Movin's command of the market than promoting Kiss.
KUBE is more worried about Hot 103.7 and vice-versa than they are about Movin'.
Everything you say is true about the Seattle market, but obviously there's something else other CHRs in other markets can learn from KQMV, as they continue to buck national trends. CHR as a format has been trending down lately across markets, with several stations that flipped to the format during the boom of 10 years ago getting out. Yet Seattle continues to do well.