First, it has to be remembered, that the planes are crap. Sat for many years in the weather in storage. Old TWA planes sitting for years, equals many issues.
DHL moved the PHX-SAN flight to the ORD flights so the legs were easier to recover if the plane has an issue.
Fifth plane is the worst and has some gear issues and heard something about a mercury spill years ago that lead to serious corrosion. Due out in November.
No other flipping so far.