As I've posted before, 247 is constantly updating their rankings. Rather than roll out rankings periodically, they take a much more fluid approach.
Marcus McWilson is one of the most recent bumps for the network, going from an overall 88 to 90. That slight bump is good enough to get him his fourth star in their rankings.
View Nebraska's Current Class Here
A.J. Natter is currently sitting at an 88, and I won't be surprised to see him bumped if he camps this summer. If not, a strong senior effort could likely do the trick.