I thought this thread is about PENETRATING backhands, not any old reliable sliced backhand possibly used to tease or change of pace.
OTOH, what is "penetrating"?
My hard slice backhand is "penetrating" against 3.5 weak players. Against 4.5's, it's an easy sitter.
The 4.5's backhand "penetrates" against me, but is an easy sitter for a 5.5.
The 5.5's "penetrating" slice backhand kills the 4.5, but it's a sitter for 7.0's.