Everything you need to know about Free Agency

The falling confetti has barely settled on the ground following the New England Patriots' victory over the Los Angeles Rams in Super Bowl 53, yet the 32 NFL teams are already moving onto building a champion for the 2019 season.

One vital component of that roster building will be the frenzied period of activity known as free agency, which begins at 9pm UK time on Wednesday March 13.

The free agency signing period marks the start of the league year, which makes for a headline-filled time. Not only does this time of the year see multiple signings of veteran players who are out of contract, it also sees high-profile trades and, occasionally, big-name retirements.

The NFL likes to coin the phrase 'Expect the Unexpected' when it comes to the games being played on Sunday evenings, but the same train of thought can be applied to the beginning of the new league year and the opening of free agency.

What is free agency?

The free agency signing period is one of the key ways for teams to upgrade their rosters during the offseason. There can be hits and misses along the way, but that won't stop teams from opening their cheque books and throwing millions of dollars at veteran players in March.

When NFL players have played out their four (or sometimes five) year contracts, they become free agents. They can hit the open market and reap the rewards during the NFL's spending free-for-all.

To put it in Premier League terms, if Liverpool failed to agree a long-term contract with Mohamed Salah, the Egyptian star could play out his existing deal and sign a new one with Manchester City, Chelsea or any team of his choosing. And Liverpool would receive no transfer fee compensation for that move.

With the salary cap figure rising each year, every NFL team will have an estimated $190-191 million to spend on their 53-man rosters in 2019. History shows us that many teams are willing to over-pay for players they think can help them challenge for Super Bowl glory.

Is it a successful way to build a team?

The results of building a team through free agency have been mixed. It is certainly another piece of the roster-building puzzle but is rarely successful when desperate teams try to salve their wounds quickly and, often expensively, through free agency.

Take two quarterback-hungry teams from 2018 as the perfect example of where things can go wrong. The Arizona Cardinals paid Sam Bradford $20 million to be their quarterback last season but had sent him to the bench before the end of the third game and cut the veteran passer in early November.

The Denver Broncos took a two-year, $36 million swing at former Minnesota Vikings passer Case Keenum. He was a below-average quarterback in 2018 and he may not even be on Denver's roster in 2019 after news broke that the Broncos are trading for Baltimore's Joe Flacco upon the opening of the new league year.

There were other disappointments. Cornerback Vontae Davis signed a one-year deal with the Buffalo Bills for $5 million and promptly retired at halftime of a Week 2 loss to the Los Angeles Chargers. But there were also some highs with Eric Ebron starring at tight end for the Indianapolis Colts and Demario Davis doing the same at linebacker for the New Orleans Saints.

Which teams can spend big this year?

The Indianapolis Colts have the most salary cap room of any NFL team with an estimated $107.7 million to spend. But don' expect the Colts to go silly - they have been prudent roster builders under general manager Chris Ballard. Unlike a year ago when they made very few moves, I expect the Colts to add some names to their championship-chasing squad, but they won't put their long-term success in jeopardy.

Other teams with plenty of cash to spend include the New York Jets ($95.3 million), the Buffalo Bills ($79.4 million), the Cleveland Browns ($79.3 million) and the Houston Texans ($77.9 million).

Of that top five, expect the Browns to remain very active indeed as they continue to build a squad that has the makings of a real contender in the AFC. By contrast, the Jacksonville Jaguars ($5.9 million over the cap) and the Philadelphia Eagles ($16.1 million over) are in financial trouble and will need to purge some veteran players before they can shop for new additions.

Who will hit free agency this year?

Each NFL team can franchise tag one star player to keep him from hitting the open market. Putting that aside for now, some big-time defenders are going to be up for grabs in mid-March.

Renowned quarterback hunters DeMarcus Lawrence (Dallas Cowboys), Trey Flowers (New England Patriots), Jadeveon Clowney (Houston Texans) and Dee Ford (Kansas City Chiefs) could all be up for grabs, providing they are not tagged by their respective teams.

On the offensive side of the ball, quarterbacks such as Nick Foles (Philadelphia Eagles) and Teddy Bridgewater (New Orleans Saints) are likely to attract significant interest. Perhaps the biggest name up for grabs this spring will be Pittsburgh Steelers Pro Bowl running back Le���Veon Bell, who sat out the entire 2018 campaign after refusing to play under the franchise tag. Rest assured, Bell will be keen to strike it rich during this offseason.

Here are some of the top players set to hit free agency in the coming weeks coming weeks

What other headlines can we expect around the start of the new league year?

There will be trades. NFL teams seem more willing than ever to trade with each other and we have already seen a deal agreed in principle that sends Flacco to the quarterback-hungry Broncos. The price is a fourth-round draft pick and rolling the dice on Flacco seems worth a shot, even though Broncos general manager John Elway has taken some heat for the move.

This will not be the last trade of this offseason. It seems nailed on that superstar wide receiver Antonio Brown will force his way out of Pittsburgh after bidding an online farewell to the team and publicly explaining why he doesn't like quarterback Ben Roethlisberger!

Brown has an ever-growing amount of offseason baggage but that said, his talent will be hard to ignore and it's looking increasingly likely he will be one of the highest-profile moves of this offseason.

There is even more talk of New York Giants star wide receiver Odell Beckham Jr. being on the trading block. That particular storyline has done the rounds before but there would definitely be a market for this game-breaking talent and I could see a scenario where the Giants are willing to move on from a player who has missed time through injury consistently during his New York career. Stay tuned on that one.