I don't believe I downed Williamson. In my first post on the subject, I mentioned, as his first attributes, that he runs good routes and has steady hands. These are terrific attributes - one must catch before he runs.
However, I disagree on the ceilings. If he can't get a decent YAC in college, how will he do so in the NFL? As for running, OU did its share as well, with a guy named Adrian Peterson. Not as pass happy has they had traditionally been.
As for comparability, they are VERY comparable. here are their player pages:
Williamson
Clayton
Williamson seems to have had a good long reception against Georgia, and the owned Troy and Alabama. The rest of the season was above average for college. As for Clayton, he has had a more consistent career at OU, about the same numbers for last year, and equitable competition. But if you combine the stats with the 2 videos, I put Clayton a notch or two above Williamson, and would not draft Clayton until 20-32 anyhow, which would put williamson 2nd round.