I'm not disagreeing about BI being a good thing, I don't know enough about pitching mechanics to make an argument either way. I'm just trying to understand what everyone is saying. I don't see how having the forearm brush the hip makes it speed up. It seems to me that the friction would slow it down.
Many don't consider this here to be a "light brush".
I prefer "light brush" over "bump," "hit" or "whack." Good IR creates a wrap; that when viewed in video, could be perceived as a "whack." The cue of "brush" vs "bump" is important to emphasize that brush occurs with good IR.
I've come across too many girls that wish to avoid the contact .... for them the word 'brush' isn't strong enough. Time goes by and they come back to me still fighting the notion. Simply be more direct in what you are asking for. The word 'brush' to some of these ladies is translated to 'almost touch, but don't really'.