How does a business get into the Google map pack?
Google says local results come from three factors: relevance, distance and prominence. Relevance is how well the profile matches the search. Distance is how far the business is from the searcher, or from the place named in the search. Prominence is how well known the business is, drawn from reviews, links, citations and its presence across the web.
An agency can change relevance and prominence. It cannot change distance. A business a few streets from the searcher will often beat a stronger one across town for the same search, so map position shifts from block to block. A report that shows one rank number for a local term hides that.