Increasing scoring / scoring rate while maintaining efficiency isn't an improvement? I'm surprised to hear you say that. Generally, as shooting volume goes up, efficiency tends to go down. Players who can maintain efficiency along with volume are rare.
This isn't true the number of shots taken by a given player usually only slightly decreases their efficiency. Especially if they're playing the same sort of role on their new team. Inefficient players typically stay inefficient and efficient guys typically stay efficient. Basketball players are pretty darn consistent overall with their play.
I just disagree.
Look at Paul Pierce as an example. In the five years where he's taken the fewest FGAs per game, he's had 5 of his 6 best years in terms of FG%. The year he took the most FGAs per game was his second worst in terms of efficiency.
Take a look at Allen Iverson. His efficiency tended to go down in relation to the volume of his shots; in the only two seasons where he ever shot 45% from the field, he averaged fewer than 17.6 FGAs. In every season where he shot more, his efficiency was lower.
Look at Al Jefferson: as shot attempts went up, his FG% went down.
Again, I will take players who maintain efficiency with an increase in volume any day. Yes, there are players who do so, but those players tend to be very good.