The reason why you should never jump early on a kicker is simple, they rarely, and I mean straight-flush kind of rare here, rarely ever repeat being top 5. And mind you top 5 is just basically the top 50% of the starters. Whether a kicker is a great NFL kicker or not, it fluctuates too much. Essentially you need a guy with a rocket of an accurate leg, on a team whose offense will drive the ball a lot, but will have to routinely settle for field goals. Its nearly impossible to predict how all of those variables will play into things.
I've seen people jump all over Wilkins after his huge year, Vanderjacht after his, recently Rackers, and no doubt I will shake my head at those that overpay for Gould this upcoming draft. Its a mistake every drafter should avoid, like being that guy that takes Peyton Manning in the late 1st early 2nd.