Ah I see. Yep that other comment I made was uselessly hand-wavy.
The point I was trying to make, starting with my initial comment in the thread, is that there is a middle ground between "we're spending way too much time devising and implementing really fancy fine grained metrics" and "we only look at revenue".
My concrete example makes this point much better, and it seems like we're in agreement, so carry on :)
If that was your point, I misunderstood your comment. Yes, there are metrics that will help you predict problems. My comment wasn't about this.