Quote 1
WILLY: Well, Bill Oliver—very big sporting-goods man—he wants Biff very badly. Called him in from the West, Long distance, carte blanche, special deliveries. Your friends have their own private tennis court?
BERNARD: You still with the old firm, Willy?
[…]
BERNARD: What is it Willy?
WILLY [small and alone]: What-what’s the secret?
BERNARD: What secret?
WILLY: How—how did you? Why didn’t he ever catch on?
BERNARD: I wouldn’t know that, Willy.
WILLY [confidentially, desperately]: You were his friend, his boyhood friend. There’s something I don’t understand about it. His life ended after that Ebbets Field game. From the age of seventeen nothing good ever happened to him. (Act 2)
To impress Bernard, Willy attempts to present Biff as a successful man. Bernard knows Willy and Biff too well, though. He doesn't really seem to buy any of Willy's deceptions.
Quote 2
BERNARD: If he doesn’t buckle down, he’ll flunk math! [He goes off].
LINDA: He’s right, Willy, you’ve gotta—
WILLY: [exploding at her]: There’s nothing the matter with him! You want him to be a worm like Bernard? He’s got spirit, personality… (Act 1)
Willy's emphasis on reputation blinds him to the reality of Biff's academic problems. By constantly making excuses for his favorite son, Willy inadvertently stands in the way of Biff's success. Biff's reputation will only take him so far if he can't even pass high school.