Low enough that it took Google nearly three engineers per successfully injected honeypot (7 honeypots per 20 engineers) and Google was only able to achieve a 7% success rate despite their extensive in-house knowledge of SEO.
I don't understand what you're trying to say here. The Google blog post says that they inserted 100 honeypots into Google. Then it says "within a couple weeks of starting this experiment, our inserted results started appearing in Bing."
Low enough that it took Google nearly three engineers per successfully injected honeypot (7 honeypots per 20 engineers) and Google was only able to achieve a 7% success rate despite their extensive in-house knowledge of SEO.