I always take this position - if you have at least a pick in every round for the class to be a "success" you have to hit on your 1st rounder, either the 2nd or 3rd rounder has to be a full time contributor, and you need to find at least two depth pieces (not even good players) from the 4-7 rounds.
You do that, and you've done OK IMO. People will focus on round 4 and talk about busts, but IMO, there isn't a whole heck of a lot of difference between a 4th round and a 5th rounder at that point. When you look at the percentages of success rate of picks, there is a clear line between 3rd and 4th round and then the differences between 4th and 7th aren't all that great.