Almost every player that is chosen needs to develop and as the draft goes on the more critical the player development aspect is because late round prospects have a lot more holes in their game.
I think one way to evaluate drafting is to see how many comp picks a team receives over time. While this does not take into account the level of draft equity it does show how many prospect developed over time to the point where they could land a 2nd contract with enough money to receive draft compensation. Using this measure the Rams have done fairly well and probably would get an even higher grade when considering the lack of draft capital they have had in recent years.