A bi-weekly challenge from Andre Mirabelli & Opturo

If the central insight of Modern Portfolio Theory is that information about returns without commensurate information about risk is dangerously misleading, under what circumstances should one report, to portfolio managers or to asset owners, the results of an ex-post performance attribution that evaluates how much of the active return is due to each type of investment decision implemented, if one is not also going to report the results of an ex-post performance attribution that evaluates how much of a relevant risk measure is due to each type of investment decision implemented?