I go back and forth, but the more I think about the draft the more I see it is one event, not so much the rounds.
In other words, there's a few hundred college players. You take turns picking (and make trades). At the end, you want the best bunch possible, however that happens.
If the 5th, 6th, and 7th round guys are great but your 1st and 2nd aren't, who really cares? You want a few impact guys. Of course, the idea is that a different guy picked 1st AND those 5th, 6th, and 7th guys still being good is better, but you just want good players.
There are too many factors that affect a players' success to expect more than a certain success rate in the draft.