I just read a very interesting blog/discussion concerning game theory pertaining to utility vs. marginal utitility and optimization. It was about football, but I believe that it translates to basketball very well. Basically, there are 2 arguments:
1. The numbers should be looked at independently without variables.
Big 3 are efficient relative to BBD/Rondo, Big 3 should shoot more. Argument- the numbers prove Big 3 efficiency and more shots shouldn't effect the numbers. Even if efficiency drops due to increased FGA, efficiency should still be higher than BBD/Rondo.
2. The numbers cannot be assessed independently. Part of the REASON that Big 3 are efficient is that the defense is forced to pay attention to Rondo/BBD. The assumption that increased shots for Big 3= increased team effiency is not necessarily true as the defense will start to employ double teams, shades, etc.. that will tend to mitigate the very factors that led to high efficiencies in the first place. As an extreme example, imagine that Doc ordered BBD and Rondo to never take another shot as long as they were on the floor with the Big 3. (this is the marginal utility argument)
I tended to side more on the marginal utility side (minority), and in a basketball discussion I also tend toward argument number 2. Now, I'm not saying that the Big 3 shouldn't get more shots, I am. Just that the numbers don't conclusively prove this.
The more I think about it, the 'drawing fouls' argument on this thread really persuaded me that Pierce needs to get 3-5 more FGA per game. The reason for this is the increase in utility that comes from drawing fouls. Plus, it gives the C's 2 ways to score when he attempts a shot- FGs or FTs. Ray and KG shoot mostly jump shots.
Edit to add: isn't this what always happens to veteran teams? They increasingly tend to be jumpshooting teams, because they no longer have the athleticism to take the ball to the basket. One of the reasons that Rondo is so important.