There are many, many benefits to commissioning, most of which can be qualitatively described and understood when considering whether or not commissioning is "right" for a particular facility or institution.
We know them by heart, but how can we quantify these benefits?
Although all practitioners know that there isn't a single project out there that didn't benefit from commissioning, it is a tricky proposition to try to predict the benefits of commissioning a particular project. It is simply speculation that deficiencies will be found and that those deficiencies, if left unidentified (i.e., without the Cx design review and testing processes), would result in problems for the building owner. To make such a prediction prior to the start of a design-construction project can be considered defamatory to the project team (project managers, designers, contractors, et al.).