I have to imagine that Brad Pitt was deliberately playing an over the top caricature of a four star general*. The movie itself is based on a book, The Operators, and both of them seem to be over the top poorly represented tales of the author’s time with the aforementioned general and the general’s staff. Sure, the war in Afghanistan is a fucking shit show that continues to this day, over 17 years later and still doesn’t seem to be a winnable situation, but the amount of stupid decisions in this story seem implausible. Looking at what happened to the general after the story was first published seems to indicate that he was only removed for public relations reason only, he was fired as a military commander by Obama, then appointed by Obama to run some pretty important programs, so while there may have been some sore feelings, it’s apparent there was no bad blood between the two.
This was a good movie, but take pretty much everything in it with a grain of salt.
*General McChrystal is the actual general referenced, but they changed his name for the movie, but not for the book.