Marginal Revolution: Very difficult questions
Points scored is the most overrated; steals are likely second, because of the risks required to get a steal and the absence of a "blown defense" statistic.
Shooting percentage, rebounding, and assists are underrated because they correlate with control, hustle, and smarts all of which have positive untracked impact.
The efficiency per minute ranking is pretty good. I also like the plus minus points per 48 minutes. One I think should be used but I have not seen is points per net possession.
A good metric, though not tracking defense well, is:
Points/(Shots+Rebounds+Steals-Turnovers)
When a player goes to the free thrown line counts as a shot, because doing so usually leads to loss of possession (hence the "hack a Shaq" strategy). One could improve the accuracy by differentiating between offensive and defensive rebounds, because the probability that a teammate gets an offensive board is far less than the probability that a teammate gets a defensive board, making each offensive board more valuable. Also, shots missed when the player receives the ball with little time on the shot or game clock might be removed to not penalize players for getting stuck with it. Kobe might for example be a last resort and thus takes most last second shots because it is simply better than any alternative at that point, despite the time crunch likely not being his fault.
It is hard to track defense because steals is the only statistic. How does one keep track of when a player is slow to rotate and provides an extra half second increasing the three point shooter's percentage?