It's definitely fluid...just doesn't seem like you can even get to "Very Good." FWIW, I definitely had "Very Good" for this during the beta with a D that wasn't as good as this team currently, but have yet to achieve it with any of my teams since 3.0 rolled out and usually have strong defensive teams. Maybe they tweaked something to make it tougher to get there, but it sure seems near impossible to get "Very High" on Strong D pref now.