Systematic enforcement.  
Lack of clear definitions
Enforcement Practices
Political sensitivities
Issues with research
Policy experts applications weights to statistical measurement
Lack of open data for necessary fields
Bias or flaws inherent in self-reported data
Analysis does not present evidence of wrong-doing in a statistically rigorous way, what it does do is flesh out an existing investigation with facts supporting anecdotal evidence that can help make the case for predatory behavior on a more systematic, portfolio-wide level. It can also provide clues about where to begin conducting an investigation, although on-the-ground evidence will be needed to confirm the suspicions generated through our analysis.
Lack of "adequate training set". To refine this methodology we need more confirmed cases of successful prosecutions. We would also need confirmed "negative" portfolios, that is, portfolios that are not engaged in illegal behaviour. 
Compare to methodology at the OAG (need of informants, etc). 
Pros:
Very interpretable.
Easy to use.
Brings in information from a variety of data sources
Mention stakeholder search?