It'd be great if you didn't put words in my mouth. The ratings aren't useful in explaining game results. Pretty much the same way in which you can't make apple cider using oranges, which doesn't make oranges inedible.
The ratings are used to assess the approximate strength of teams you are not playing against. Since looking at individual player salaries does not give you an idea for the players' skill configuration, understanding how ratings are formed can help you with getting an idea of what the players in question are like.
The ratings are not always useful in explaining the score of a particular game, and they will never be, no matter how you rebalance them. Games are won or lost based on individual match-ups, not on game ratings. In this particular example, no matter how skilled your centers are, your look inside will bomb spectacularly if you don't have guards that can pass them the ball efficiently (which may be due to poor passing skills, or great OD by the opposition). No matter how you slice the IS calculation, it will never include the passing of the guards, nor should it.
Instead, you can look at your PP100 and see that despite your great inside skills, you got poor shots -- and think what was the reason.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."