NFL championships are won on the field on Sundays every winter, but championship teams are built during the offseason.
That means free agency, which isn't the preferred team-building method by many NFL general managers, becomes a very helpful tool for some teams around the league.
Adding veteran players, some who have length injury histories, can be problematic for teams, though. They should always approach this time of the year with careful skepticism and do due diligence before taking the plunge on any player that comes with risk.
Let's take a look at some of these risky guys teams will talk to, and likely sign, this summer.
Reggie Bush is a playmaker that many teams could definitely use. However, teams need to realize the risk that comes with signing Bush to a long-term contract for No. 1-running back money.
Bush isn't a traditional primary ball-carrier, that's the problem. He's better utilized as a pass-catcher out of the backfield and as a change of pace to a bigger and more capable every-down back.
Then there are the injury problems. The talented RB has a low durability and injury-proneness that teams should look out for, too. However, after missing a slew of games in his first five seasons with New Orleans, he has missed just one game over the past two seasons in Miami.
The Dolphins have a stable of suitable runners on their roster and will not likely be forking over the type of money Bush will be trying to get. That means someone else will.
Steven Jackson could very well retire. If not, he would be a risk for any team willing to give him a shot in 2013.
Jackson's injury problems are common knowledge, but he has played through them for the majority of his career. Sure, he's missed a game or two here or there, but he's always pushed through them and stayed on the field despite being noticeably banged up.
The nine-year veteran back will turn 30 over the summer, the dreaded number that signals the beginning of the end for NFL running backs.
Jackson could be a good pickup, if he doesn't retire, but he should not be regarded as a quick fix for a primary ball-carrier in 2013.
The St. Louis Rams have some of their best players hitting the free agency market this offseason. Danny Amendola, the team's top wide receiver, could find himself bathing in money and playing for a higher profile team come next season.
Amendola can't stay on the field. He missed nearly all of 2011 and five games in 2012 with injuries. But when he was on the field, the Rams looked like a different team offensively.
He demonstrated an excellent ability to get separation and use his hands to make spectacular catches. His big-play potential opened things up for Sam Bradford underneath and took some pressure off of the young signal-caller.
That alone makes him a valuable commodity for a team that's willing to take the gamble.
Benjamin Watson has had a solid career catching passes in New England and then Cleveland. The Browns leaned on him a little more heavily than the Patriots, and he showed he has the ability to carry that heavier load by recording some of the best seasons in his nine-year career.
The problem with Watson is his age, but that isn't it completely.
Multiple concussions have left the 6'3" pass-catching tight end with a warning label around the league. He could be fine, but anyone that underwent three concussions in one season should be approached with caution.
Sebastian Vollmer has been a wonderful blocker for Tom Brady in his first few years in the NFL. He's proven to be a powerful and technical expert that can handle some of the best edge-rushers around the league.
But, a back injury slowed down his excellent 2012 season.
Injuries happen. You get them and they disappear. But tweaking something in your back, especially as a big and tall lineman in the NFL, could be a recurring problem.
If New England doesn't bring him back, and it should, Vollmer will likely get top dollar on the free agency market. There is vast potential here but also a good deal of risk involved due to the lingering nature of his back problems.
Osi Umenyiora, 31, recorded six sacks in just four starts for the New York Giants in 2012. Still, the aging veteran competed in all 16 games during the season as situational pass-rusher.
Contract disputes have marred the big man's time in New York. He's even threatened to sit out an entire season in the past.
His best days are clearly behind him, but he still has some gas left in the tank to help a team that could use a pass-rush boost.
Age is certainly a factor here, along with injury concerns after some knee issues in the past. Buyers should beware but also be open-minded in negotiations.
This isn't a guy who is going to demand Mario Williams-type money and then not deliver. He should get some consideration for a big deal, but not one near those astronomical numbers.
Another big-name pass-rusher hitting the open market this offseason is Dwight Freeney. Freeney has been a staple of the Indianapolis Colts' pass defense for the past 11 seasons.
With Peyton Manning already gone out of town, Freeney could be next if a team is willing to take a gamble on the 32-year-old this summer.
He was converted to an outside linebacker/defensive end hybrid in the Colts' 3-4 defense in 2012. His numbers, partly due to injuries, have continued to decline as a result of aging and scheme changes.
His best days are clearly behind him but he could still be worth a short-term contract for a team in need of edge-rushers.
Cincinnati's Rey Maualuga was suspect at best in the Bengals' playoff loss to the Houston Texans. The hard-nosed linebacker had a poor game in pass coverage and continued to be outplayed by undrafted rookie Vontaze Burfict.
Did he get comfortable and settle in or was something else wrong?
Whatever it is, teams should be wary of a player of Maualuga's caliber wearing down at the end of the season, when it matters most.
Maybe a change of scenery and a fresh start would do wonders for the linebacker. Either way, there's a risk there.
New Chicago Bears head coach Marc Trestman would not commit to keeping 35-year-old linebacker Brian Urlacher around next season.
There is good reason, too.
Urlacher is no longer the fast and dominant linebacker that read plays and blew them up before they could develop. He used to be able to cover tight ends and sit in deep-middle zones to effectively prevent big gains.
Those days are gone. Not only is he on a physical and productive decline, but untimely injuries significantly hurt the Bears' 2012 season.
He's a big name that could bring in a sizable contract, but should be looked at for what he is and not what he once was.
Cornerback Tracy Porter is known for making big plays. He had a pick-six to seal a win over the Pittsburgh Steelers early on in the 2012 season.
He was set to have a big year for the Denver Broncos after that big start.
But things didn't turn out that way. Porter was forced to sit for much of the season after seizure symptoms kept him off the field.
Denver's defense improved in his absence, which doesn't do much for his stock.
Overall, Porter is an aggressive corner that takes chances and they sometimes pay off with big dividends. He has decent size and good speed but also a propensity for injuries.
He has yet to complete a full 16-game season, playing in just 49 of the 80 games during his five-year career.