SERP Diversity

This is fascinating to me:

The sites with the 10 highest scores win the coveted spots on the first search page, unless a final check shows that there is not enough “diversity” in the results. “If you have a lot of different perspectives on one page, often that is more helpful than if the page is dominated by one perspective,” Mr. Cutts says. “If someone types a product, for example, maybe you want a blog review of it, a manufacturer’s page, a place to buy it or a comparison shopping site.”

So then what happens? If there’s not enough diversity, what’s the next step? I’m wondering here how much work is done by calculation and how much of it is “hey, that just doesn’t seem right, let’s tweak it.”
(Separately, and selfishly, I wonder if these sort of tweaks ever get pushed out into Enterprise PageRank. I’d like to see the effects of them on GSAs that crawl content I’m very familiar with.)