UPS is the only thing that will bring UPS down. You don't have to talk to all that many Amazon, Post Office, or Fed Ex employees to know that those places get things wrong all the time and have workforces that hate the management.
The day Amazon finally figures out how not to pack a glass vase into a box big enough for a dishwasher to fit in might be the day they are truly ready to compete on a fleet wide level of any kind.
They won't rise above a level of UPS. Chances are much better UPS and it's out of touch upper management will drag the company further below it's current benchmarks if not completely off a cliff.