Whislt exams are well and good and show someones ability to take info onboard they are no indicator about how the person is going to perform in the role.
I get a lot of Grads come through my Dept at work and you would be surprised how many havent got an ounce of common sense! I had a Grad with a 1st in Maths from Oxford nearly have a breakdown on me after just 4 weeks as he was dealing with situations where he couldnt find the answer in one of his textbooks!!!!
So whilst 98% in exams may be nice, you may be worse at the actual role (pilot/engineer/doctor/etc) than the person who just scraped through. So knowing 98% of jack sh1t doesnt really come into it if you can't practically deliver the role required of you.
J.