What week 1 means is relative to every different situation and team. Being ranked high in week 1 doesn't mean you have start sucking.
Holding any NFL team to under 250 yards of offense (with most of that coming in garbage time), and less then 40 yards total rushing, is impressive. Kevin Smith rushed for 1000 yards last year. He's pretty good. Calvin Johnson is the toughest WR in the league to defend. Pettigrew was one of the best TEs in college football. It's not like the Lions O is made up of scrubs.