Kyle Williams has not been a starting Nose tackle for 4 years. he's been a starting UT or Under Tackle in our previous scheme. His duties in the previous scheme's where to shoot the gap between the Guard and Center, and cause havoc in the backfield. In our new scheme he'll be asked to control 2 gaps, and take on a guard and the Center, and hold the point of attack. And he is gonna have a hard time doing that due to his relatively small size(for an nfl DT) and his short arm length. So while Williams can contribute to an NFL 3-4 defense, he's simply not a 2 down NT.