Based on the descriptions in the article, aside from isolating the teams, this is very much what they did. The difference being that they didn't have a second

Based on the descriptions in the article, aside from isolating the teams, this is very much what they did. The difference being that they didn't have a second team dis-assemble and actually reverse engineer the product to write a formal spec for how it functioned. Instead they did A/B testing to ensure that the output of the known product produced the same output as the reference implementation, reportedly without examining how the black box worked.