How you going to measure playmaking? 
Example  - Stockton had 10.5 asst worth 0.4 points each, commiting 2.8 to worth -1.0 points, so his playmaking value was 1.4. For Curry? (6.4 x 0.4 - 3.1 x 1) 
Put in whatever values you think are missing or s/b adjusted.