The win in operating costs is impressive, bordering in the unbelievable (27x). Does anyone have a clue about where the win comes from?

It's almost certainly meant to be 27%, not a factor of 27.

I am fairly confident that is a typo. The paper says "Our analysis reveals that RNG topologies are 9–45% cheaper than fat trees with equivalent oversubscription ratio." The blogger probably left off the % sign.