Hi Tom, thanks for reaching out. Unfortunately, we do not support averaging at this time in Apptio BI. We are currently monitoring this, as we look to expand our Calculated Metrics capabilities in the future, so users can create more interesting metrics using operations like Count, Sum, Avg, Min, Max, etc. It really does help us to understand your use cases, so thank you for providing that.
You did find a pretty good workaround, but I would recommend creating the metric in ApptioOne - Cost, then exposing it via Data Source Management in Apptio BI, so you can report on it. There are also already a good amount of average monthly metrics in ApptioOne - Cost today, so you might not need to create it from scratch.
Let me know if this helps.
cc: @Matt Wroblewski @Matt Gerow
#ApptioBI