Hindsight bias.
After Garnett and Kobe came right out of high school and started kicking butt almost immediately (especially the former), a lot of players came out in the next 5-7 years. Who knew so many would start sucking?
Take
this Bill Simmons column from right after the 2002 NBA Draft, regarding the top two picks:
Six months later, to the day,
he wrote a follow-up. To his credit, he admits fault, which is more than I can say for some sportswriters.
Who knew Jay Williams would decide to be an idiot with his motorcycle?
...And yes, I know what you're thinking: Who knew Yao Ming's feet would betray him?
Not that it matters--Yao's in the Hall of Fame. Jay's not.