I never really thought about how I hold my lenses. Having no formal training in photography, I just did what felt natural. With a 70-200, my left hand goes on the bottom, my fingers can work the zoom ring, and the bottom of my palm can give support to the bottom of the camera via the battery grip. Also my elbows can tuck in tight to my body, for extra stability. I can shoot at 1/60 at 200mm, sometimes, depending on my coffee consumption.
I tried holding zoom ring from the side/top...Really? People try to shoot like this?
At any rate, having never seen her work, its not fair to judge, but poor technique in probably a good indicator.