If you read the NTSB’s report, you’ll note that they address this explicitly: the front half of the plane more or less sheared off, causing the back half to pitch up before descending.
That was the "CIA analysis" that was published on the front page of Newsday after the crash that had absolutely nothing to do with the hundreds of eye-witness accounts. Hundreds of people saw a missile fly thousands of feet up from sea level to the plane, which subsequently exploded. Nothing these people saw had anything to do with what happened to the plane after it broke up, which is what the CIA/sanitized-NTSB report addressed. Their further absurd claim that the explosive residue found on the wreckage from the plane was tracked in on the bottom of some passenger's shoe was similarly insulting to the intelligence of everyone who was following the investigation. Combined with the purging of several lead investigators - decades-long veterans of many crash investigations - who insisted that the plane was shot down by a missile, everything points to a missile attack and a coverup.