Teams are entering the first phase of offseason roster building, so in the coming weeks, all 32 franchises will have to decide whether to extend their own players, judge whether or not to apply franchise or transition tags, and determine which free agents would be worth pursuing in the free-agent market.

We've recently provided an analysis of the most important players to extend on offense and defense. We also have free-agent rankings by position, and we've published multiple versions of our 2020 NFL Draft Guide. The macro question for roster building is how to use the three primary levers of talent acquisition and retention (draft, extension and free agency) in harmony to provide the most benefit in terms of the ultimate denominator: wins.

How teams pull these levers — while staying under the salary cap — is determined by need, front office preferences and, at least in part, by luck. If a team doesn't hit on its draft picks, it's hard to find worthwhile players to extend, so the vacuum must then be filled in free agency.

[Editor's note: Available to all of PFF's EDGE and ELITE subscribers, PFF's Free Agent Rankings Page consists of three-year grades, PFF WAR and in-depth analysis for all of the top NFL free agents. Contract information from our friends at Over The Cap is also available. Subscribe today for access!]

Traditionally, free agency has been the most costly avenue for buying wins overall. But we shouldn't assume all positional units provide value via free agency equally. The assessment of the individual player is paramount in making spending decisions, but looking at league-wide trends by position can provide useful context for edge cases and negotiations. With the combination of PFF's wins above replacement (WAR) and contract values from Over The Cap, we can compare how different levels of spending in free agency, extensions and the draft have affected the value derived for different positional units.

In this article, we'll dive into the defensive positions and compare the different contract dynamics to what we saw for offensive positions.