I had to research this further as I could not possibly believe that Mississippi was #2.
Not the point of your post (as as an Oregonian I appreciate your bringing attention to this), but I'm just focused on Mississippi.
The chart doesn't mean that Mississippi has the 2nd best overall academic outcome in "overall" performance. It just means they beat their "demographic expectations" by one of the highest margins in the country.
Removing the warping of the data here, MIssissippi is like 30th to 35th nationally on absolute scores. BUT - to your point - Oregon still sucks. 38th to 44th overall.
Sorry - total detour.