Because the better teams we play will be passing the ball a lot more, thus limiting our 3/4 base sets.
Everything I have read on him is he has drastically improved his coverage skills. Teams tried throwing on him to no avail. If he isn't the BPA then take the CB from Bama. There will still be opportunity for a qb of the same talent as smith in the late first early second. Pick 33 is like another 1rnd pick, IMO.