Cgeorg, I've got inconsistent revs/rotation every few shots. Could that be a problem with my release/timing? Maybe something I'm not doing in my follow through?
While in a video you can sometimes see something associated with this, I think it's really much easier to learn to pay attention to your body, and feel these things. Did the ball come off your hand earlier or later? Did your thumb exit the way it normally does? Maybe you hung up a bit (less revs, maybe more side rotation), or it slipped off early (more revs, maybe less side rotation). Maybe your arm was farther forward than normal at the point of release (more upright? slower feet? Probably got more revs, but maybe too much side rotation?) or farther back (excessive lean? fast feet? Probably resulted in less leverage and less rotation) Did the weight of the ball feel the same on your fingers? Did it feel heavier? (probably more revs) Lighter? (Probably less revs - maybe your wrist was slack?)
I can tell you on just about every shot, blindfolded, if I pushed it or pulled it, how much side rotation the shot has, and how many revs I got on it, just by feeling it off my hand. That's not to say I can do the same thing consistently on every shot, but I've learned to feel what *did* happen, so that I can make a correction. As you learn to feel this, you'll probably start noticing that on bad shots, some of the same things keep showing up. Then, you know what should take priority in your practice sessions. For me, it's always forward lean - other things may creep in, but they tend to be symptoms, where excessive forward lean is the cause.