Each year, signings during the summer and leading up to the start of the regular season change the complexion of the following year's free agency. Some of the more notable signings of players heading into a contract year since the start of training camp include Seahawks wide receiver DK Metcalf, Chargers safety Derwin James, Colts offensive guard Quenton Nelson and 49ers wide receiver Deebo Samuel.

Nelson reset guard market on a four-year, $80 million contract extension with $60 million of guarantees, where $41 million was fully guaranteed at signing. The deal makes Nelson the league's fourth-highest-paid offensive lineman at $20 million per year.

James did the same for the safety market. His four-year extension averages $19 million per year. There are $42 million in guarantees. Slightly over $38.58 million was fully guaranteed. 

Metcalf and Samuel were two of the latest beneficiaries of an exploding wide receiver market. The Seahawks gave Metcalf a three-year, $72 million extension. The $24 million-per-year deal has $58.22 million in guarantees, which includes the biggest signing bonus ever for a wide receiver at $30 million.

The Metcalf contract provided a blueprint for the 49ers to reach an agreement Samuel. He signed a three-year, $71.55 million extension averaging $23.85 million per year with $58.167 million in guarantees where $41 million was fully guaranteed at signing. The maximum value of the deal is $73.5 million because of incentives. 

Here are 15 players to keep an eye on during their contract year:

Lamar Jackson, QB, Ravens

The Ravens and Jackson ended contracts talks right before the regular season started in accordance with his self-imposed deadline for a new deal. Jackson, who represents himself, reportedly turned down a five-year offer worth $250 million with $133 million fully guaranteed. The offer had the second-highest average yearly salary and money fully guaranteed ever in an NFL contract.

Jackson chose to play on his $23.016 million fifth-year option because he was adamant about getting a fully guaranteed contract. The Browns gave Watson a fully guaranteed five-year, $230 million contract in connection with his trade from the Browns to the Texans in March. The Watson deal is an anomaly as subsequent quarterback deals, particularly Kyler Murray and Russell Wilson's $46.1 million and $49 million respective five-year extensions with the Cardinals and Broncos aren't fully guaranteed.

Negotiations are expected to resume next January after the regular season ends. Jackson is destined to start playing the franchise tag game if both parties remain firmly entrenched in their positions on a fully guaranteed contract. The exclusive franchise designation will be most likely. Four of the last five times quarterbacks have been designated as franchise players the exclusive tag has been used. Jackson would be prohibited from soliciting an offer sheet from other teams with the exclusive version.

The 2023 exclusive quarterback franchise number will be the average of the top five 2023 quarterback salaries (salary cap numbers with some minor adjustments) at the end of next year's restricted free agent signing period on April 21. It currently projects to $45.248 million. This number is subject to change depending on new quarterback deals, contract restructures, pay cuts and/or releases between now and then.

Tom Brady, QB, Buccaneers

Brady briefly retired after the Buccaneers' lost to the Rams in the divisional playoff round. His retirement was short-lived, as he changed his mind days before free agency started in mid-March. It was hard to imagine Brady walking away after one of the best seasons of his NFL career in 2021. The 45-year-old threw for a league-leading (and a career high) 5,316 yards and 43 touchdown passes last season. His 67.5 completion percentage was the second-best mark in his career.

It will be tempting for Brady to keep playing beyond this season if he continues to defy Father Time. There could be tremendous costs to his personal life, however, as his wife, supermodel Gisele Bundchen, isn't happy that he didn't stay retired.

Brady already has a post-career transition in place. He will become Fox Sports' lead analyst on NFL games and work as an "ambassador" for the network with a focus on "client and promotional initiatives" once he decides to permanently hang up his cleats. Brady's deal is reportedly worth $375 million over 10 years. It is the most lucrative contract in sports broadcasting history. The value of Brady's contract with Fox Sports is more than he has made from his NFL player contracts. None of Brady's NFL player contracts have averaged $37.5 million per year like his broadcasting deal.