INDIANAPOLIS -- Building an NFL roster is easy. It's all about drafting and developing your own players. Unless you don't draft well. Then all you have to do is sign free agents. Unless, of course, there are no good free agents to sign, in which case the answer is simple: Sign the average ones, and give 'em a bunch of money to make it seem significant.

In truth, of course, the magic formula is that there is no magic formula, at least not lately. An analysis of the past three free-agent markets evidences nearly every imaginable outcome.

Via the chart at the bottom, compiled by ESPN Stats & Information, we can see teams that reacted aggressively to poor draft classes -- sometimes with disastrous results (Jacksonville Jaguars). There are teams that all but ignore free agency, both to their general benefit (Green Bay Packers, Carolina Panthers) and detriment (San Francisco 49ers). Most teams try to blend a mix of free agents with their draft classes, a rational approach that works better in some cases (Denver Broncos, New England Patriots) than others (Tampa Bay Buccaneers).

The fickle nature of free agency, and the myriad ways that unrelated factors can impact its success, leaves more teams preferring to minimize market involvement. Speaking last week at the NFL scouting combine, Indianapolis Colts general manager Chris Ballard articulated a consensus view. Ballard, hired last month to build a better team around quarterback Andrew Luck, said "you have to be right on the player you sign."

He added: "That's where my fear of free agency comes in, making sure we know exactly what we're [getting]. Is he a good fit? Is he the type of person that's going to come in and the other players are not going to resent him because he's making a lot of money?"

The dramatic recent rise of the salary cap, from $120.6 million in 2012 to $155.3 million in 2016, has reinforced and exacerbated another ugly fact of free agency: The best players rarely hit the market. Teams flush with cap space usually can meet the pre-market demands of their pending free agents, leaving talent-hungry teams to overvalue and overpay second-tier discards.

That's why the Pittsburgh Steelers, for example, are a rare participant. As the chart shows, all but two teams dished out contracts with a combined total value of more than the Steelers' $86.9 million. It's difficult to argue with the results; the Steelers' 32 victories during that period have been exceeded by only two teams.

"We've always been a draft, develop, keep-our-own [team]," Steelers general manager Kevin Colbert said. "I think you're seeing more teams doing it. And as a result, you're seeing less and less quality free agents. There's an inherent danger in that, because some of the players who are hitting the market with the number of dollars that are available, [they] might not be quite worth what they're going to get paid because of the supply and demand. And I think that's reflective in a lot of the early cuts, the five- and six-year deal guys who usually get cut after two or three.

"You have to be careful about the free-agent market and not overpay for maybe an average player."

Consider the Jaguars' spending spree, beginning in 2014 with running back Toby Gerhart, guard Zane Beadles, linebacker Dekoda Watson, defensive tackle Ziggy Hood and receiver Tandon Doss. The Jaguars moved on from all of them within two years. They have gutted their 2015 class as well, having released defensive end Jared Odrick and cornerback Davon House while trading tight end Julius Thomas. Those eight players alone were signed to contracts that included nearly $75 million in guaranteed money, a case study for players whose market value didn't match their value to their new team on the field.

Last week, of course, general manager Dave Caldwell said the Jaguars "have to be disciplined." He added: "We're going to set a limit for the guys we target and we're going to be aggressive for the guys we want, [but] we can't be careless with the money."

The Broncos, on the other hand, are among the handful of teams that view free agency as a necessary deterrent against reaching for needs in the draft. In theory, a handful of holes filled in March and April can allow for a less rigid draft approach. The Broncos have signed fewer unrestricted free agents than a majority of NFL teams, but the dollar total of $236 million ranks No. 12 -- an indication that general manager John Elway has pursued and signed notable players for much-needed roles. That list includes cornerback Aqib Talib, defensive end DeMarcus Ware, safety T.J. Ward and receiver Emmanuel Sanders, whose contracts included nearly $65 million in guaranteed money.

"I feel more comfortable if we can take care of some needs in free agency," Elway said. "I believe that there is a good blend in both. Free agency is there for a reason. … I think we can supplement some needs that we have through free agency, because I don't like going into the draft with big needs. If we go into the draft [with a long list of needs], we have a propensity to reach. We try to stay out of that situation."

And that, if anything, might be the most reasonable approach to free agency: Find your comfort zone, a place built from deep knowledge of your own roster, and maneuver aggressively within it. It will vary from team to team and general manager to general manager. When you pay big, make sure it's for a player who has a chance to perform at a high level within the context of your team. And then, hold on.

As we can see, there is no straight line between free agent activity -- at any level -- and success.