To be able to acquire the massive defensive tackle in the fifth round is amazing. It represents one of the biggest steals of the entire draft.
Bleacher Report's Eric Stoner filed the following scouting report on Williams earlier this month:
An ideal “War Daddy” for 3-4 teams, Williams could play either the defensive end or nose tackle spots in both one-gap and two-gap systems. He might not ever have impressive sack or pressure totals, but he can be an anchor and the most important player on a defensive front, similar to DE/NT swingmen Vince Wilfork and Haloti Ngata.
Considering that Seattle runs a hybrid defensive front, Williams' skill set will fit its scheme. I wouldn't worry too much about projections of him being a fit solely in a 3-4 here.
Williams can come in and spell Brandon Mebane as a run-stuffing tackle as a rookie this upcoming season. He can also play a Red Bryant-type role on the outside in certain defensive sets.
Again, there are concerns over injuries here.
Williams had his knee scoped following Alabama's victory over Notre Dame in January (via The Boston Globe). This caused some to worry about his ability to make an immediate production and led to his fall to the final day of the draft.
For his part, Williams is confident that the knee injury is behind him:
I had that scope just to clean up (the knee) after the national championship...I didn’t get to run at the combine, which was disappointing for me, but I made up for it with the running I did at the pro day. It’s been 100 percent. No dramas so far.
At 6'3" and 320 pounds, Williams possesses nearly the same frame as Red Bryant (6'5" and 326). He could easily spell the former fourth-round pick on the outside. That being said, lining up over the shoulder of the center seems to make much more sense early on.