Brees is a gunslinger, but was helped by Sproles as he forced the D to cover the flat and short route. (anyone can close on pierre thomas). Without Sproles, defenses can drop back - Brees has 6 picks so far this season, already half of what he had all last season.
Now they're facing the Lions - I don't think the Saints will be putting up many points. Also check into the status of Jimmy Graham - he was listed on the injury report.