"We deliver more on-time packages than anyone else."
True, as far as it goes, but UPS also delivers more late packages than anyone else.
Because UPS is weighted toward ground transport, their per-day package volumes are still considerably higher than FedEx (which is the volume leader in the overnight business).
In on-time %, FedEx is way ahead of UPS.
I guess that when 85% of the packages you move don't have a delivery commitment, you can throw them into the "on-time" column so your stats look good.