I have watched it, and here's Bayley's kick, and Sasha's... look at the difference. Sasha absolutely belts her in the back as opposed to pushing off like Bayley. She should know not to kick her so hard, it's called professionalism. I wouldn't call it a freak accident. She kicked her hard... Freak accident is Joe injuring Tyson Kidd.
Here's Bayley doing it a night or two before...
Here's Sasha... If you can't see that it's much, much harder I don't know what to say.
Again, not saying that she tried to injure her or that she did it on purpose, but she used a LOT of force in that kick. It's something you simply don't do when someone isn't facing you. You learn that right away in training. Again, not saying that she's the direct reason her career is likely over, but Christ, it's just not cool to kick someone like that, especially in the spine.
Sasha has a history of doing stupid things. It's not the first, nor will it be the last, unfortunately.