Does Smarter Balanced Think 15% of 5th Graders are "College and Career Ready" in English?

I'm working on a longer piece trying to decipher what Common Core and Smarter Balanced are saying about growth in ELA/Literacy after 8th grade.

Specifically, Smarter Balanced (one of the two big Common Core testing consortia) recently released their achievement level recommendations for grades 3-11. This is particularly noteworthy because the achievement levels are on a continuous vertical scale. That is, all grades are scored on the same scale. As I understand it, these scores should be comparable across grades. That is, if a 4th grader gets a 2560 and an 11th grader gets a 2560, they are at the same level as far as Smarter Balanced and their interpretation of the Common Core are concerned.

Here's what it looks like for ELA/Literacy:

Notice how the expected/required growth levels off after 8th grade, when there is a two year gap in testing (apparently?). Essentially the same amount of growth is expected in grades 9, 10, and 11 as in 8th, and considerably less than the elementary grades.

And notice how the cut score for a "4" in 5th grade is virtually the same as a passing "3" in 11th grade. Smarter Balanced thinks 15% of 5th graders will achieve this level.

Thus, consulting their estimated percentage of students at each achievement level graphs, we see that Smarter Balanced thinks that 15% of 5th graders will be college ready in ELA/Literacy, and 41% of 11th graders will be. The 5th grade rate of actual college readiness as 10 year olds, not just being on track for it eventually, is over a third of the 11th grade total.

I noticed a while ago that the 8th grade standards were extremely close to the "college and career readiness" anchor standards, and wondered how it would play out over time. Turns out they're sticking to that idea.

At the end of the day, these "rigorous" standards think you're pretty much set with your learning in ELA/Literacy if you're meeting the 8th grade standard. You've got a little to learn about reading, writing and literature the next four years, but not much.

I... just don't get it. The harm is that "rigor" is being pushed down to the lowest grade levels, but for not much benefit in high school. Am I missing something here?