Some of our users find it useful, for example, to know how much of a trade a particular counter-party can absorb. While it doesn't establish the efficacy of the manager (or even come close), we find it interesting in terms of individual entity trading power. Readers' mileage will certainly vary. Based on your feedback, we'll try to be more clear about those points in future reports.
I'm even less convinced about the usefulness knowing "how much of a trade a particular counter-party can absorb". And somehow deriving this information from the current book size (as opposed to available capital) also seems somewhat dubious.
Moreover, absent the AUM (or leverage) and asset mix, this number won't tell you much about the actual size of the book.