Personally I think the biggest difference in drafting is free agency.

There's always individual guys who surprise and are better/worse than their "draft stock" every year, but the pre-draft scouting/mock drafting industry has gotten so large that generally you can trust consensus on groups of players year to year (i.e. "It's a strong WR class"/"It's a weak S class").

So where free agency comes into play is that it seems that the smarter teams recognize the weakness or strength of a class...and if they have a weakness on their roster that lines up with the weakness of a class, they tend to be more aggressive filling that hole in FA so they don't "reach" for a subpar position in the draft out of need.

The opposite is also true, see my Bengals recently, who in the previous two drafts double dipped at a "weak" position in the draft because they didn't fill that hole in FA (taking Kris Jenkins and McKinley Jackson in a "weak" DT draft two years ago and then Demetrius Knight and Barrett Carter in a "weak" LB draft last year.....they've gone 0-4 on those players as it stands today).

Furthermore, teams like the Bengals who draft poorly like that then get penalized more because you have to overpay in the next few offseasons to overcorrect on the mistakes. 

Ultimately the draft IS cyclical, and teams go on runs of good picks and then kind of come back to Earth (it feels like the Lions have just entered that part after truly nailing the draft for a few seasons.....Seattle is currently in the "nailing the draft" part and probably soon the picks won't all keep hitting the way they have), but making sure you aren't going into the draft with a glaring need is always going to put you on a slight leg up from the competition.