I think the comments highlight the general issues that the Mavs face compare to the "inner city" clubs. Clubs based within 10 minutes or so of the CBD can retain a lot of their juniors for seniors. A kid who lives in Colonel Light Gardens can start off playing basketball at the social level, then play for one of a number of clubs within a par 5 of home (god forbid that Toorak Tractor travel any further north than the car park of Wildie) Then once "Pippa" has finished school and heads off to Uni, she can still continue playing for her club because she is still living at home with mummy and daddy. Then once she has finished Uni she gets a job in Parkside doing "something in PR" and still plays for her club.
Now look at Mavs. "Cheryl" lives at Wistow, she starts playing social at Mt Barker, gets into the Mavs, but also plays in her country league. Goes to Mt Barker high, finishes school, gets a job in Adelaide doing "something in sales". Moves in with a few girlfriends into a stare house at Plympton. Instead of travelling to the Hills to play basketball Saturday night, she is partying hard with her flatmates.
I think you'll find if you sampled 100 juniors from Sturt and 100 juniors from Mavs who were playing at U12 (say then 10) and were aged 20 now, I think you'll find probably 85 of the 100 from Sturt are still living at home and probably less than half of the Mavs players still live in the area.