Originally Posted by tari813
Probably because when u jump without the ball your squatting down futher and swinging your arms up. Try to dip the ball down so when u jump up your swinging your arms up too.
That was going to be my response too. One can probably count on not being able to jump as high with a ball in hand as without, but you can minimize that difference with a couple of small tips.
Scm5, I'm with you, I was having the same issue for a minute there. Then I stumbled upon (or rediscovered) the idea that tari813 just dropped up above. I realized I was essentially running too straight up, attacking the rim too straight up, dribbling too straight up, and then elevating too straight up.
Essentially, the upright dribble, attack, and jump was zapping me of my bounce. Once I consciously began bending my knees a little and getting lower on my approach and takeoff (off one or two feet) my dunking has stepped back into normal zone. It will add a few inches back almost immediately. Just something worthwhile to check.