haven't really studied it, but anecdotally, they are two of the hardest to separate. they both weigh all ratings in a substantial way. probably speed, bh, pass push towards a sf, reb and blk towards a big. not sure if there are 2 big forumlas, there's at least 4 overall, which i think of pg/sg/sf/big, but i am not sure if there's pf and c. pf ranking on the board seems to value all ratings highly, including spd/per/bh/pass, so if you are one of those well rounded players with lots of stuff, it tends to be better to hold reb/blk if you can and squeak in as a sf. perhaps counter intuitive, but its like the game expects sfs to be more well rounded, so it tends to be a much bigger problem to have guys with 120+ combined bh/pass coming in as bigs. opposite of how it normally works, normally its great to be getting sg credit for pretty good reb/lp, you pay so little over there for those. bigs with bh/pass is much different.