There are enough people on this planet staking their reputations on one claim or another that we should expect people to "see things coming". Those many millions of people making grand claims are usually, but not always, incorrect.
There is a very important quote to remember here, if you're ever told by someone to make an economic bet:
"Markets can remain irrational longer than you can remain solvent."
You may know, for a fact, that a commodity is overpriced, that a stock is overvalued, or that the entire market is operating under "irrational exuberance". Okay, but in the history of the discipline, no economist has ever been able to predict when the party will stop. Prices can soar to many multiples of their values, and selling short will bankrupt almost everyone who thinks they know, for certain, when the party will stop.
Every once in a while a few economists stake their reputation on a market crash and are correct, and sometimes they get a little too full of themselves, write a book on their ability to forecast the market, and disappear into obscurity. Michael Pettis seems he may very well be one of these people.
Just about every economist I've read has thought the party would stop in China soon, no nation can sustain growth rates like theirs indefinitely. Short of the Chinese discovering and secretly using cold fusion or a perpetual motion machine, I would think.
So why is it the "Pettis hypothesis"? Sheesh.
I look forward to another person fleecing poor investors to fade into obscurity. The man who saw this crash coming was dealt a good hand, that's true, but he won't always win.