There were some reports that the rams were approached to trade back. They didn't want to for fear that Simpson would be picked. So it they were not so set on Simpson and they traded back, maybe a bigger CB and a quicker LB could have really strengthened the D.I just don't know what defensive player the team could have selected at #13 that would make much difference as a rotational backup as it's doubtful anyone would crack the starting lineup barring an injury.
Some like Bain, but I just don't see him as a good fit. Plus, whenever I watched Miami I came away more impressed with his teammate.