There is still a little bit of confusion about how they look at grades. The actual number that is reported means very little in the WCS calculation. There has been many post about it and you could find them by digging.
In an effort to normalize the way schools calculate GPA and weight on different factors, they take your class rank and school profile to develop an academy ranking or GPA.. If you got one C and everyone else in your school got the same C in that class then it would not affect your ranking. If you took all basic courses and have a 4.0 GPA, the academy will not treat it as a 4.0 for ranking. A GPA of 3.2 and a class rank of 500/1000 is not the same as a GPA of 3.2 with a class rank of 50/1000. These are extreme examples but kind of show the process. If those B-s are in Honors/Pr-AP classes they will not kill your chances.
There is no way to actual control how the academy will see your school profile. What you need to focus on is taking the most challenging courses available to you and doing well. If you have lower grades and class rank, you need to do well on the standardized test to average out the scores. You also need to look at the other areas to help pull up the lower academic ranking.
As my friend @Cerberi
says, you are competing against other kids who may have done better and you need to look at what else you can bring.