OK, I have done the calculations. If Duncan played in the East, he would have won all 18 1st-round series, 15 of 18 2nd-round series, and made the Finals 9 times.
If Lebron were in the West, he would have won 9 of 12 1st-round series, and 7 of 9 2nd-round series, and made Finals 3 times.