He only took *four* isolation jump shots all season at Kentucky, and nearly every shot he took was a jump shot, so he didn't generate a lot of free throw attempts. The rare times he took it to the rim (only about 10% of his FGAs), he didn't finish efficiently. He also wasn't a very good defender-- a smart guy with a good frame, but not a guy you could count on generating stops at the next level.

So Booker was a shooting guard that everyone knew was a phenomenal catch-and-shoot guy, but people weren't sure if he was a strong shot creator, a strong foul generator, or a strong defender. Now, I had him at 8th on my Big Board (I tweet my Big Boards for posterity for just this reason!), so I was clearly higher than the teams that drafted, because I believed he could shoot off the bounce at the next level... but I do understand why teams didn't have him as a lock Top 5 guy. Four iso shots is a *really* small sample, lol.

Furthermore, this was before shooters were trending as the top priority in the draft. There were six guys 6'9+ drafted before Booker, only one of whom shots 3 at above a 30% clip. In today's NBA, Booker is a stone cold lock Top 10 guy, because even if teams did think "he's just a catch-and-shoot knockdown guy who moves the ball pretty well and has strong positional size," that's just viewed as more valuable today than it was then.