From 538's website "Just to emphasize how unlikely that Democratic pickup in Washington’s 3rd District was, our midterm forecast gave Gluesenkamp Pérez just a 2-in-100 shot of defeating Kent. That is the upset of the cycle thus far. While Kent always seemed likely to be a weaker GOP candidate than Herrera Beutler, a Republican losing an R+9 seat is highly unusual in a midterm when Democrats control the White House."