Actually, he was the second best CB last year as a true Sophomore. Then again, the only corner better than him was the top corner taken in this years draft which means every single corner in this last draft would have been considered at best the 2nd best CB on LSU.
Many would agree with you not taking TM7 in the first round. After all, he wasn't even really a division 1 prospect coming out of high school because the scouts said he couldn't play there.
Since then he has just smashed records and is the definition of the word playmaker but maybe you are right, we don't need a playmaker on defense, just someone that is technically sound.