Yes RB has an impact in all salary formulas. But as long as a player is in a guard formula they can have as much IS/ID/SB as possible for free. At least to the point where they change into a big man formula.
Since the season 37 changes, these secondary skills probably are being applied into the salary formula, although of course the details on that are slim. My best comparison now is between two guys who have nearly identical SG skill levels at the time of salary calculation and somewhat significant inside differences.
P1: 15+/18/13/10/10/3 - 1/6/6/8
P2: 15/18/13/9/11/8 - 4/11/7/15
P1 actually got to 16 JS this week so his sublevel was clearly higher (and my training log would reveal that) and he has slightly more OD I believe. But in terms of SG formula skills, they're essentially the same. P2's additional 3 IS, 5 ID, 1 RB and 7 SB gives him a salary $112 higher than P1.
So, um, yay?