The Detroit Lions suffered their first loss of the season, but are still one of the premier teams in the NFL. They're 5-1, just behind the defending champion Green Bay Packers in the NFC North, and lost what was a close game against the 5-1 San Francisco 49ers. So it's no surprise that they're generally holding in or around the top six or seven teams in week seven power rankings.
ESPN just released their week seven rankings, and they've got the Lions at number six, down two from last week, but that's more because they needed to adjust and get the 49ers in there:
6. The one worry for the Lions is not being able to power run the ball in the second halves of games. (Clayton)
That's a legitimate worry, and a just reason to drop the Lions a couple of spots instead of just one. It's more important than win/loss records, and if the Lions can't get Jahvid Best running after the first half, they'll be in an awful lot of trouble down the road.