If history teaches us lessons about the future, then teams have a lot to learn.

Consider the success rate of the wide receiver position. Historically, wide receiver ranks as one of the most targeted positions in the first two rounds of the draft (more than running backs and tight ends combined), and yet they experience the highest attrition rate in the NFL.

Of the 43 wide receivers talented enough to be chosen in the first round in the last 10 NFL drafts, guess how many have been invited to a Pro Bowl? The answer is a mere nine -- not a ringing endorsement for teams that continue to go all-in early. By comparison, 22 of the 47 first-round running backs and tight ends went on to a Pro Bowl.

So, if not wide receiver, which positions would be wiser investments early in the draft?

Before we get our hands dirty, a more advanced measuring stick is needed to evaluate NFL production; a checklist of Pro Bowl selections won't suffice. For that, we call upon Pro-Football-Reference.com's newly launched NFL player metric, Approximate Value (AV). Without delving into the gory mathematical framework, we'll describe AV as a tool that attempts to capture a player's seasonal contributions in a single number, no matter what position he plays. Consider it an NFL version of John Hollinger's NBA Player Efficiency Rating. Offensive linemen, quarterbacks and linebackers are all graded on the same objective scale.

This system allows us to study talent depth across various positions in the draft which offers a guide to help identify value opportunities outside the bank-breaking first round. Teams shouldn't feel obligated to pony up A-plus money for an A-minus prospect if they can wait to spend B-plus money on an A-minus prospect of the same position in a later round. On draft day, evaluating talent depth can be just as vital as evaluating the individual talent itself.