Traditional methods of collections evaluation and assessment that focus on the journal container are increasingly in tension with both user experience and academic discovery systems design, both of which prioritize the individual item or article. This paper explores the potential applications and limitations of a new metric, the full text coverage ratio (FTCR), for revealing new insights about academic serials collections. Given a discovery service search that represents a particular subject area, the FTCR is the ratio between the number of items returned by a search scoped to full text and its corresponding "expanded" or un-scoped search. While the idea itself offers the potential for valuable and actionable insights, it may be that further analysis and refinement is required before it can be more widely adopted. This paper will describe these ratios in more detail, explain how they can be calculated, discuss some premises or prerequisites they require, present some of their limitations, briefly describe an application already pursued at one particular institution, and suggest additional applications and potential future directions for research in this area.