In the course of an NFL season, contract disputes and the emergence of younger talent can force players that would be stars in other situations to look for other forms of employment.
It's one of the reasons that free agency has become the most popular route for players over the years in sports across the world, and it's a reason that this year's free-agent class will be hotly contested across the league come March.
After being under-appreciated in their current cities, some of these stars will have a chip on their shoulders, both in contract negotiations and training camp, as they hope to prove worthy of that "star" designation.
Big names from Joe Flacco to Wes Welker will hit the open market come March, but only a fraction of those elite players will change teams come 2013. Here's a look at four guys who appear destined to wind up in a new city, but will continue to star when that change takes place.
Note: For an unofficial look at this year's complete class of 2013 free agents, check out NFL.com's list.
CB Mike Jenkins, Dallas Cowboys
Jenkins was the odd man out in Dallas this season after the team signed Brandon Carr in free agency, drafted Morris Claiborne in the first round and had time to reflect on the monster contract Orlando Scandrick signed in 2011.
Jenkins was hurt during OTAs and training camp, but he returned to the lineup this year and ended up making a huge impact. With injuries to Barry Church and Scandrick depleting the secondary, he returned to his familiar role on the outside and showed several glimpses of the guy who was a Pro Bowl candidate just three years ago.
He's young, he's motivated and he wants to be wanted (via Brandon George of the Dallas Morning News). That in mind, there's a slew of teams that would love to make him one of their starting CBs for the next few seasons.
With Dallas facing a salary-cap crisis this offseason, it's going to be tough to meet his salary demands, take care of higher priorities like Anthony Spencer and also restructure other deals (Tony Romo) in the process.
The writing is on the wall for Jenkins, but that won't make him any less of a priority for other teams interested in secondary help.
RB Reggie Bush, Miami Dolphins
Bush had a comeback season for the Dolphins in 2012, rushing for nearly 1,000 yards and compiling eight total touchdowns in a dual role with the rest of the Miami backs.
He's positioned himself as a sneaky option for a team looking to add a layer of speed and play-making ability to an RB situation that's already steady with a lead back (Dallas, New York and St. Louis could be options).
After struggling to live up to his Heisman billing during the first half of his career, Bush is now a mature back who's figured out how to survive in the NFL. Don't look now, but next season will be his eighth—well longer than many expected him to last after he struggled in New Orleans.
As a third-down back who can occasionally handle a bigger load, Bush is worth $5-7 million for the next two to three years. Although he reportedly wants to be back in Miami "badly" (via Will Brinson of CBS Sports), the emergence of Lamar Miller and the potential of Daniel Thomas make him expendable (via Chris Wesseling of NFL.com).
WR Mike Wallace, Pittsburgh Steelers
Jason La Canfora of CBS Sports reported that the Cleveland Browns are the front-runner for Wallace's services, but there are a great number of teams (Seattle) that would love to add him to their current collection of WR corps.
Where will Wallace land in '13 free agency?
Wallace had a troubling year in 2012, criticized for drops and inconsistent play. Pittsburgh needed him to step up with Ben Roethlisberger hurt for a number of games in the middle of the season, but he faded away and let a lack of focus characterize what could be a lasting memory for black and gold fans everywhere.
Still, Wallace is young (26), one of the fastest receivers in the league and is a great complimentary piece worthy of a big contract. Whether he gets overpaid or not is another discussion entirely, but there's no doubt Wallace will have a big season next year wherever he plays.
FS Ed Reed, Baltimore Ravens
Could the unthinkable happen in Baltimore? Ray Lewis retired, and Ed Reed is iffy at best to return to the world champions at this point in the process.
According to general manager Ozzie Newsome (via Jamison Hensley of ESPN), the Birds aren't giving up on Reed returning to the team full-time in '13. However, they will not place a franchise tag on his head, and that could prove to be troublesome with so many other free agents set to command money elsewhere.
As K.C. Joyner notes, the New England Patriots would be one of Reed's biggest suitors in free agency, able to give him a solid contract and promise him the same kind of freedom in NE's secondary that he had in Baltimore.
Reed is on the decline—we all know that. However, look at stars like NBA legend Jason Kidd. Sometimes, players transcend their age, and Reed is a candidate for that award after a great 2012 season and an important interception in Super Bowl XLVII.
No matter where he signs this offseason, Reed will keep on making plays roaming center field. He and the rest of the players on this list have a good opportunity to change teams while not losing the ability to be an NFL star.