Worthy does not have the body type needed to play nose tackle in base defense: he's too light in the pants. You want a squatter body in the middle, one that won't easily get leveraged by the center. And when he has been able to stay healthy, his performance on the field has been underwhelming. He seems to be afflicted by that double curse: an underachiever who cannot stay healthy. I think there is a decent chance he doesn't make the final roster this year.