If the Rams like all 5 guys they could trade down 4 spots and guarantee that at least one of them is still available.
I think that's been the Rams trade down strategy ever since the Bobby Wagner fiasco: if they trade down they only go so far as their player pool allows them. 5 guys lets them drop 4 spots. (If they had 8 guys graded the same they could drop up to 7 spots, etc.)
The mistake they Rams made in 2012 was they had pick 45 and the two guys they had their eye on - Bobby Wagner and Mychal Kendricks - were both available. The Rams traded back to 50, thinking that one of them would still be available. But they went 46th (Kendricks) and 47th (Wagner) and the Rams were left holding the bag.
Draft trades since then suggest that the Rams learned their lesson. But man, was that ever an expensive lesson ...
AlbaNY_Ram