As to Math vs. Reading: scores aren't apple to apple. These are interval rather than normal scores. Math tops out twenty points higher than reading.

I was thinking the future numbers were about acceptable levels of growth rather than projections. They may have an error range factor that lowers the acceptable minimum growth score from a projected score. Since overperformers have lower projected growth in points (like say 1 points growth,) then the acceptable factor could drop that by 5 points.