Every day I receive calls about plant problems. It is often very, difficult for me to determine what the problem may be over the phone. So, I ask for plant samples or pictures, depending on the description of the problem.
In this case, this maple died very suddenly. This does not sound like a disease or insect problem to me. Yes, maples can have problems with Verticillium wilt, but let's not be too quick to blame this disease. Further investigation should be done. First of all, the drought and heat this summer have been very, harsh on tree health. Unfortunately, if that tree has any preexisting decline problems, this stressful weather will not help!
If a root rot or wood decay fungus infects the declining tree.....yes, that can cause a sudden death. The symptoms of the maple in the above pictures are very symptomatic of Armillaria root rot. For more info, you can check out this link: http://www.na.fs.fed.us/spfo/pubs/fidls/armillaria/armillaria.htm
There are some species of this fungi that are just saprophytic (survive on dead wood), but there are some that can be parasitic (cause disease). I can’t tell you which came first. It is still possible that that the girdling root/deep planting killed the plant and then Armillaria invaded later. But, Armillaria root rot could have caused the tree to die too.