The upside: Even the worst defeats tend to feature a bright spot or two.
Running back Beanie Wells scored two rushing touchdowns in his first game back from a toe injury.
Rookie quarterback Ryan Lindley completed 17 of 24 first-half passes while making his first NFL start. He led a 96-yard touchdown drive on the Cardinals' first possession.
Second-year tight end Rob Housler caught eight passes for 82 yards.
Receiver Andre Roberts caught nine passes for 92 yards.
Peterson had a 26-yard punt return.
Punter Dave Zastudil had a 45.2-yard net average.
The Cardinals ran 77 offensive plays, 23 more than the Rams ran.
Inside linebacker Daryl Washington collected his ninth sack of the season.
Arizona gained 234 yards with 15 first downs in the first half.
Looking ahead: The Cardinals visit the New York Jets in Week 13.