It seems that there are a lot of questions or misconceptions in regards to the way that the current set up of free agency works. To answer any questions, I'll explain the different levels of free agency and then list the current Lions players that the individual tags would apply to. Keep in mind, this is for the current system, and will likely be void come next round of free agency when a new collective-bargaining agreement (CBA) is agreed upon.
The first thing that must be understood, is by "seasons accrued", a player must be on the active roster, Injured reserve, physically-unable-to-perform list, or designated inactive for at least 6 weeks of the season. So a guy like Tim Toone has yet to accrue a season, as he was on the practice squad and was never active.
Exclusive-Rights Free Agent (ERFA):
These players have accrued less than 3 seasons with their current contract expiring. In this situation, the team has the right to offer a "qualifying offer", which would be established in the CBA. Once the team has done this, the player either has to accept the offer, or sit out the upcoming season.
Current Lions who would become ERFA under the current CBA:
Restricted Free Agent (RFA):
RFA's are players who have accrued at least 3 seasons but no more than 5 seasons and have a contract expiring. Teams then are allowed to tender, or place a specific draft pick value upon the player that they would receive in compensation if a player rejects their offer and signs with a new team. If a player does not sign with a new team before the deadline (established in the CBA), they must accept the teams offer or sit out the season.
Current Lions who would become RFA under the current CBA:
Unrestricted Free Agents (UFA):
UFA's are players who have accrued at least 6 seasons and their current contract is expiring. These players are free to negotiate with any other team unless the franchise or transition tag is placed on them by their current team.
Franchise tag - Depending on salary offer, a player can be "exclusive" or "non-exclusive". If a team offers a minimum of the average of the top five salaries at the player's position for the current year, or 120 percent of the player's previous year's salary, or the average of the top five salaries at his position as of the end of last season, whichever of the three is greater must be offered to distinguish the player as exclusive and the player may not negotiate with any other team. To be considered non-exclusive, the team would offer a minimum of the average of the top five salaries of last season at his position, or 120 percent of the player's previous year's salary. With this tag, other teams can make offers, and if the player signs with another team, 2 first round draft picks would be given to the former team.
Transition tag - A team must offer a minimum of the average of the top 10 salaries of the prior season at the player's position or 120 percent of the player's prior year's salary, whichever is greater. If another team makes an offer, the team has the right to first-refusal and is able to match the offer and then keeps the player. If they do not match, they lose the player and are not awarded any compensation.
These tags may be placed on any level of free agent.
Current Lions who would become UFA's under the current CBA:
That pretty much covers it, but as I said, the status of many of these players will change with a new CBA. Also, I do not claim to be an expert, just a fan who wanted to be more informed and did some research. If anything is wrong, let me know as well as posting a link to the correct info.