Well, motion definitely helps, but the bottom line is. The Rams secondary is dog poop.
That may be true ... but the Rams Pass D is better than the Eagles Pass D. With both playing 8 games ...
Passing Yards given up = 1,748 (R) vs 1,980 (E)
Passing TDs given up = 8 (R) vs 16 (E)
Interceptions = 4 each
Sacks = 15 (R) vs 25 (E)
QB Rating = 85.9 (R) vs 97.2 (E)
So the Eagles passrush is better, but their secondary is worse than the Rams secondary.
Therefore if the Rams secondary is "dog poop" ... I would hate to see what you think about the Eagles secondary.
P.S. Dak accounts for HALF of the passing TDs the Rams have given up. It went into the game at 4, and left at 8.