Underrated Ian Williams a key to 49ers' defensive line

Daily 49ers blog for NBC Bay Area website: On his way out of town, 49ers' star defensive lineman Justin Smith says Ian Williams is one of the NFL's best nose tackles. http://www.nbcbayarea.com/news/sports/Ian-Williams-May-be-a-Key-to-49ers-Defensive-Line-304424491.html