I remember loving this movie as a kid. Looking back, it's hard to believe how many spin-offs Disney produced.
While it has a plot about friendship, better treatment of animals, and advancing in life, that probably wasn't the reason you liked it.
No a dog playing basketball was mind-blowing. At least to my nine-year-old self. My dog at the time was not the basketball player. But he did give it a mean stare once.