There are many casual/fairweather/bandwagon fans that come and go supporting the NBA whenever they please due to a certain player or team doing well(Jeremy Lin for instance right now). But what would the diehard fan understand more than the rest? Is it understanding the salary cap and how much each player is getting paid and how much each player SHOULD be valued at? Is it knowing how to name every starter on every NBA team? Knowing players that most people who support the NBA don't like Derrick Brown and Solomon Jones? Is it delving into the advanced statistics to understand the game in a deeper degree such as our own resident Durvasa? So what do you think seperates a die-hard fanatic from the casual fanatic?
I think if you know nearly ever player on every team except for those non-guaranteed contracts and such. Knowing statistics off the top of your head from retired players to current players. Things like that make you a die hard NBA fan.
Probably shooting your tv with a shotgun when your team loses would qualify you as a die hard NBA fan.
The fan that sticks with their team through the good and BAD years always cheering on whether up 5 or down 20. That's a die hard fan. The one who watches every single game rooting for a win even though the team was eliminated from playoff contention 3 months ago.
I think it can be measured a number of ways, many of which the OP hit on in the original post. For starters, as mrm32 alluded to, you have to stick with "your team" through thick and thin. I also think you have to watch games simply because it's NBA basketball. I'm talking about about games that the casual fan wouldn't have any interest in watching. I also think you have to have an advanced knowledge of NBA rosters, at least 7 or 8 players deep on most rosters and maybe 10 deep on the better teams.
If someone attempts to kill you repeatedly but you just never die, and you so happen to be a fan of the NBA... you are a die hard NBA fan.
to stick for years with a team, and know all the players from your favorite team. fairweather people following Jeremy Lin, cant name 5 players with the knicks outside Lin. Not to root only for the trendy team (this year the knicks, last year Miami, other years Lakers, in the 90s the bulls).
If you're watching a NBA game and your shaft just happens to be hard and coincidentally you end up dying... you're definitely a die hard NBA fan in my eyes...