When dunking a basketball on a 10 ft hoop jumping off one leg, is it incorrect to drag the non jumping foot?

when dunking on a 10 foot basketball hoop jumping off one leg, does dragging the other non-jumping foot cause a decrease in vertical? For dunking all i need is 2 inches but i cant seem to stop dragging my right foot when im jumping off my left foot on take off and making a huge skid from my sneaker in the driveway. is this causing a decrease in my vertical or something, like is it that much of a problem that if i fixed it and did not drag my right foot i could get those 2 extra inches to dunk?