<p>I agree with Sam Lee. The problem is really with the shifting standards of grading. Basically, there is no consistent standard. Being 15% below the mean might translate to a C in some classes in certain schools. It might translate to a B in some classes. It might translate to a D or an F. Heck, sometimes it might even translate into an A- (which is what happened to a guy I once knew who took a highly grade inflated class. He was a full standard deviation below the mean of the total score of a class and he still got an A-, and he was laughing about it later. Basically, nobody in the class got lower than an A-. And this was an engineering class at MIT, no less). </p>
<p>So, again, the real problem is the inconsistent grading. Sometimes you really can do very little work, not understand the material at all, and get an A anyway. Sometimes you can work extremely hard, understand the material extremely well and still get a D or an F.</p>