Damn I return home from the meet and finally log on tonight and what was clear as day from my perspective sitting 10 rows up directly up from where she falls and my eyes were focused on Morgan as I was watching her move closer to the front. McGee clearly steps on Uceny's foot. Morgan was on as much as I could tell watching very intently a straight line so no deviation to the left as some have speculated. Foul 100%. Really glad Morgan isn't hurt. I probably screamed louder in angst for her misfortune than anyone. But part of my screaming is her inability to correct this technical flaw that while not fully responsible is no doubt causing a higher likelihood of such collisions.
Had exact same position in London when she fell, just higher up and also in Zurich 2010 when she went down and DNF'd. The falls 2-4 years ago had me pay careful attention to her technique. As I watch her warm up even just a minute or so before the start I notice her doing drills that over emphasize backside mechanics. If you do analysis of her form you will see she leaves the leg extended long as she pushes off rather than trying to recover the foot by utilizing her quad more and pulling foot quickly under her butt.
Would improved technique have prevented all of these falls? No but it certainly has contributed in my opinion and all too frequent vantage point.