I'd have to go back and really dig in, but my initial impression was that they struggled where I would expect them to but still held up pretty well in the run and pass game for the most part.
The Fuaga penalty was a killer. There is no getting around that.
Also, the full slide away from Verse on the final play, leaving him 1-on-1 with Moreau, was less than ideal, THOUGH Moreau did actually do a decent job and Carr had time. The Rams out-foxed the Saints on that play, simulating pressure from the field, then bringing it from the boundary and allowing the Rams to drop underneath their quick-game concept and cover everything up.
Honestly, this is where the WR depth (or lack there of) finally came back to bite them. Valdes-Scantling should've been working to a second window rather than just sitting there, covered. Carr sees it and is waiting for him to do exactly that (it's why he doesn't try to scramble, he knows the second-window throw is there), but because Scantling just sits there, Carr has to hold onto the ball for way too long and Verse forces the fumble.