Ball pocketing and spin

I do think the idea of "brushing" across the ball is a bit overrated, but can be used to help understand spin creation early on. As Devin mentioned, on many shots there is pocketing and a small amount of upward brush across the ball. In high speed video we can see that the ball will normally leave slightly (1-2 mains across) lower than it arrived. Also there is the pull down and snap-back demonstrated with video of poly, contributing to what many would consider a brushing effect.

Then there is the ball pocketing contributions. The pocketing alone isn't creating spin, but the 'up and across' racket head movement during pocketing as the racket moves thru the ball, that will add torque in the direction of the swing. During pocketing, there is not only the deflection of the strings, but also a flattening of the ball. So while there is a aspect of brushing I mentioned earlier, there is this pocketing that creates a certain "lock-up" on the ball to the strings that will act much like a soccer kick where they "bend it like Beckham". During the added friction of the ball flattened on the strings, the net lifting 3D "up, thru and across" force can be imparted to the ball via torque, to create spin. I think it is important to add in the idea of how lifting from the hips and legs can greatly augment the upward swing of the arm to enhance the lifting effect to the ball.

I hope this helps to explain how the brushing and pocketing work together to create spin.