When I think of core torque and how it applies to pitching, I think of offset timing. Making sure the FSR is what's actually creating a hip snap. It's that hip snap that creates a torque within the torso that now must be resisted after approximately 1/4 turn. This is a specific sequence that'll aid in the whip of the arm.
All of this is a NO TEACH!! If she has a correct sequence, good drive mechanics, achieves brush, and has good resistance (all 4 points). The core torque will be a result of these key indicators.
Agree on most of this and made a small edit to my earlier post. I think saying focus on core torque can be confusing versus focus on the core to create core torque is better served.
This is very much a sequence that needs to be taught and mastered. I will quote Rick and then add to another post below. "Every key movement in pitching begins in the midsection/core and either works its way down or up."