I don’t think we saw the same video.
I have to disagree. The play starts with Wambach running in front. The Colombian girl closed from her right rear and initiated the contact. It does look like Wambach elbowed back, which is a natural reponse when you’re being bumped from behind, but Wambach never broke stride or looked back. It’s mechanically possible that the right cross could have been, as you suggest, a matter of the Colombian girl twisting and throwing her hands up to regain balance ... except that Wambach, who had never looked back, went down like a shot. So she was hit pretty hard.