Yeah all those issues that ball players have technically are due to either:
1) Lack of strength in the proper places to "look" and "act" good on their run-up/plants
or
2) Lack of practice
Sometimes there's a 3rd:
3) Bad structure for that particular jumping method. But truth be told, you're going to have a bad structure if SOMEONE tells you to jump differently (say a two footed jumper meets someone who tells him to jump off one leg and he sucks - that could be a structure problem but MOST LIKELY it's a lack of practice and lack of strength in the proper places).
When I started to jump 12 years ago after doing no kind of sports up until that point (up until being 15 years old) - obviously I was completely uncoordinated and had a 12 inch jump. But over time I'd say my jump technique got pretty good just by jumping day in and day out to the rim. I had no understanding whatsoever of training/techique or anything like that, just jump.