I would worry. Ram D last few weeks <> Rams D weeks 1-5.
Carolina couldn't run either in week 7, and they kept Cam somewhat in check (15-17-204-1, 10-26). Houston did run wild week 6, but they snuffed Schaub (15-26-186, knocked out) in a game that was a blowout for the Rams.
Rams D weeks 1-5 vs QBs: 21 pts / game (1pt/20yds, 4pt/TD, -1 int)
weeks 6-8 vs QBs: 14 pts / game
It's starting to look much more like the Rams D of last year which was rather stingy. Interesting that Jo-Lonn Dunbar came off suspension week 5 and started week 6. He was the SLB last year, moved to WLB this year, since DROY candidate Alec Ogletree had taken his old spot. With Laurinaitis at MLB and an impressive front four, the talent is there to dominate weaker offensive lines (the inconsistent Carolina OL and a very banged up Seattle O-line qualify here, Houston not so much especially in regards to run blocking). The secondary is the obvious weak spot on the Ram D with glaring holes at safety. The injury to Cortland Finnegan week 4 may have also been a boon to them as he was terrible.
If Locker gets the time, he can burn them deep. If he doesn't get the time, he may not finish the game.
Note the Rams do get up for these divisional games more so than others and the Monday Night hangover could come into play, so Locker's not a bad start. There just may be better.