Watching Miss ST @ Kansas ST on 9/8/18. Miss ST QB loses control of the ball while in the process of throwing a pass when hit by a Kansas ST defender. Initial call on the field was "fumble". Kansas ST recovered the ball. After a lengthy review it was ruled that since he had control of the ball at the point of contact, it was not a fumble. There were no complaints and play resumed.

My question is Why isn't that a fumble? It seems to me the defender did his job knocking the ball loose.