I love NBA but I don't have that much knowledge to make sport analysis a living.
Trust me, I really wish that I was able to do so. The problem is, I have yet to come up with any way to actually quantify defense, especially since they didn't even start keeping track of blocks and steals until the 1970s. A lot of what happens on defense doesn't show up on the stat sheet. If you play suffocating defense and force a team's best player to pass the ball at the end of the shot clock, that doesn't show up anywhere.