It's no secret that the Patriots are looking to shore up their starting defensive line this off-season. With the departure of Richard Seymour and Jarvis Green, the Patriots are looking everywhere for the player who can fill the starting spot on the defensive line. It starts with the upcoming draft.
Williams is 6-2, 327 lbs and is rated as the best DT in the draft, after Suh and McCoy- which means he's most likely a first round pick. He's been drafted as early as the top 10 and is usually gone by the 15th pick. If the Patriots want to grab him, they'll most likely have to trade up. However, he is most likely going to continue to play DT in the NFL, which means that trading up to grab him wouldn't be in the Patriots best interest as he'll fill a spot already taken by the recently drafted Ron Brace- the position of "Bench" behind Vince Wilfork. I expect this visit to get a sense of Williams as a player and to see how he'll affect the Patriots draft board.
Thomas, on the other hand, is 6-4, 330 lbs and expected to be a mid round pick- perhaps even dropping to the fourth round. The value of Thomas in the 4th round would be great enough to take a pick- he has the strength and body length (an inch and a quarter longer arm span than Williams) to perhaps transition to the DE position. Thomas may as well end up as a DT in the NFL, but the fact that we wouldn't have to trade up to get him makes him a much more reasonable selection.