The 49ers must replace more than 50 percent of their snaps up front following the departures of McDonald and Justin Smith. ... Arthur Jones and Kendall Langford are solid starters on paper, but the Colts aren't going to get the benefit of the doubt until they hold the Patriots' ground attack under 150 yards and three scores. ... The Titans have little to boast beyond Jurrell Casey, who recently made his overdue debut on NFL Network's Top 100 Players list. ... Until 2014 second-round pick Stephon Tuitt emerges as a solid starter, the Steelers' line will remain vulnerable against the run.