Williams has that unstoppable factor. Some of the catches on his tape im watching and like.... ok no way he can come down with it in that triple coverage while getting absolutely blasted by the safety... then the dust clears and there he is with the football.
He just doesnt need to do all of those things (at least hasnt yet). Hes never covered. His body control and hands are unreal. Has that Dez, Julio, Green, Nuk thing going for him where when you need a play, and the defense even know you need a play and are going to him -- he still makes the play.
Plus, hes done it against the best. Time and time again. All the top DB's that everyone loves in this draft; that everyone says are Day 1 starters and potential pro bowlers -- Williams has beat. Sometimes easily.
And Williams may have looked like a faster better route runner on tape if the majority of his tape was against the level of competition Davis faced. Our perceptions are often based on a comparison to what we see around the player. Easier to jump off the screen, easier to look faster, smoother, etc... against lesser athletes.
Davis may have a higher ceiling bc hes more advanced in some of the technical stuff while having the same, if not better, physical measurements.... but hes also got the lower floor having not been challenged much by a high level of competition.
Williams not only produced against the best -- he got better in the biggest moments. To me -- thats huge and may be the biggest distinction. Some guys just get better and better, the better/harder the competition is and the brighter the lights get.