Maybe it's time to think about a 11-15-15-15 center instead of a 15-15-15-7 guy.
Until PGs with IS=14 and SGs with IS=16 (both with DR 20, of course) will exist in the game, I don't think they will be stopped by anything less than ID=20 and SB=18. A player with these stats and good RB (at least 17) can't have any offensive skills because he's already at 250k salary. Meanwhile, the PG and SG I mentioned have 250k salary COMBINED with elite offensive and defensive skills, while our defender is nothing more than Serge Ibaka or Kendrick Perkins (we all saw what they did against Memphis...nothing).
I Think that kind of PG an SG are stoped by SB, not ID in the Bigs.
And talking about salary... The same PG and SG mentioned will have the same 250k salary with IS=1.
And for Bigs it's the same, with Passing=16 have the same salary.
We (as BB comunity) HAVE to train balanced players, exploit their potential and stop making full primary Skills that are expensive, not salary/efficiency and no one want them in the market and few teams can afford.