Sentence:  McNamee describes their grip on the company as “the most centralized decision-making structure I have ever encountered in a large company.” Their power <WSD>dyad</WSD> is possible only because Facebook's “core platform,” as McNamee puts it, is relatively simple: It “consists of a product and a monetization scheme.” 
Meaning of the word marked with <WSD> tags:  A set of two elements treated as one; a pair.