Mr. Hill makes no mention of what signals intelligence revealed about this Syrian Arab Army (SAA) position, occupied for some six months before the "Coalition" attack on it.
Let's focus on that.
It beggars the imagination that there was no SIGINT collection activity in Syria or that its requirements would not have included targeting all the areas in and around Deir ez-Zor.
By way of comparison, the Russians and Syrians maintained a SIGINT facility near al-Hara which "was responsible for recording and decrypting radio communications from every rebel group operating inside Syria." Note the use of the language "decrypting," "every," "rebel," and "inside Syria."
Are we to believe that the U.S. has no such capability in Syria and had no interest in radio traffic out of and into the site it struck? This willful ignorance, this supposed ignorance, of the U.S. forces is not believable. That targeted unit sat there for some six months and the U.S. gleaned no information as to its identity from radio traffic, let alone from (a) other photographic evidence and (b) the logical role that unit played in Syrian defenses rather than ISIS defenses? Really? It really struck analysts and commanders as being part of the ISIS dispositions?
 is a liar.
And this has implications respecting what we most assuredly know about ISIS and al-Qaida communications everywhere in Syria and, hence, about the dispositions and movements of those swine, and about the clearly pretend war that the U.S. has "waged" against its ISIS and al-Qaida allies in this dirty war. Read the Shane Harris article cited in the notes below and then tell me that ISIS and al-Qaida units cannot and could not be hounded to death by highly targeted "Coalition" military operations. Yet, inexplicably, mysteriously, ISIS lives on and on and on. It's just so hard to find them.
Alternative explanation: The U.S. is lying about not knowing the unit it struck on September 17, 2016 was a unit of the SAA. There was no mistake involved. The U.S. commander intended to attack a Syrian government position.
 "Its Own Report Data Indicates Pentagon's Slaughter of 100 Syrian Troops in Deir ez-Zor Was Deliberate." By Adam Hill, Russia Insider, 12/8/16.
 "Captured Russian spy facility reveals the extent of Russian aid to the Assad regime." By Oryxspioenkop, Oryx Blog, 10/6/14.
 "How the NSA Became a Killing Machine." By Shane Harris, The Daily Beast, 11/9/14. Money quote: "This was the most sophisticated global tracking system ever devised, and it worked with lethal efficiency."