BB was a young man when he traded Bledsoe to the Bills. He still had something to prove to himself, his team, and the league. The trade was thought out, and he rolled the dice that the Bills would screw it up, which they eventually did.
Now, BB has much more ego. It's only naturally for men of great power and prestige to underestimate his opponents, and be blinded by his own greatness. He could think, "Who cares, the Bills would screw it up again, even if I send them Tom." So I wouldn't just write off Grap just because BB is willing to send him west. Make Darth Vader pay for his mistakes!!