I have found out, again and again, that I screw my dunks and jumps up because whenever I plant I tend to have my chest oriented quite a bit towards the ground and I look into the ground most of the time. That REALLY screws everything up, from not being able to use my glutes and jumping "pulling my chest up" to jumping forward.
Now I have managed to correct that somewhat by excessively trying to look up to the rim when I plant (I'm talking about two footed plants here but applies to one leg as well somewhat) and it did some good as I was quickly able to dunk, but this problem still persists. Sometimes even when I actively think to look at the rim my body just can't pull it off and my chest goes down and forward.
Same stuff happens in my squats. I tend to bend forward a lot if I'm to go deeper into my squat. Not sure what's going on here, I've tried to figure it out but it doesn't make any sense. Maybe I need to really squeeze my glutes more to prevent that from happening? Maybe it's a mobility issue (I have thought again and again and I can't localize what kind of mobility thing is it - hip, upperbody (?), what?), I just can't figure it out.
Any help? It could apply as well to some people around here (although I'm definitely in a worse shape than a lot of you in this subject)
Just watched your 145 PR squat. You don't flex that far forward in the bottom of your squat, especially given long femurs and low bar position.
As for jumping think how long you've been jumping the way you are now...how many reps you've done. I think it's fair to say that the current neuromuscular pattern is pretty deeply ingrained. It will take some consistent focus and work to change that.