Ian W.;
Re, "So whatever the reason UPS 1354 was low, it may be common to other (unreported?) close calls "
A good FOQA Program will already have a form of "Early descent" or "Too Low 2 minutes before touchdown" or some variation of the event.
While such close calls may go unreported, (not very good safety culture behaviour), any FOQA Analyst who's doing his/her job will have ensured that the program has such events and that the results are routinely passed on to operations, flight safety, training/standards for corrective action. It is almost a certainty that this kind of event occurs in flight data.
Analysis takes a look at all factors including weather, ATC distractions, circadian time frame, precision or non-precision approach, etc and makes sure that that knowledge is passed on to the appropriate managers and that crew calls are made by the pilot group's FOQA representative (not the company) to understand more about such an event and to pass on the learning.