If there is one continuing theme around the National Football League, it is that change occurs on a yearly basis. Veterans who haven't performed up to par are replaced with cheaper, younger alternatives.
It even happens to some of the best players who have ever stepped onto the field.
For example, the Chicago Bears made the decision to go with rookie Jon Bostic over future Hall of Famer Brian Urlacher. The end result was the conclusion of one of the greatest careers in modern league history.
San Francisco traded in the consistent play of one Alex Smith for a high-octane and high-upside youngster in the form of Colin Kaepernick.
Meanwhile, St. Louis bid adieu to long-time running back Steven Jackson in order to go with a myriad of youngsters at the position.
These stories could make up a novel that makes Atlas Shrugged look like a Where's Waldo? book.
This slideshow will focus on nine veterans who simply must step up in 2013 in order to keep their jobs throughout the duration of the season and into the following year.
All contract information provided by Spotrac.
San Diego has some nice young alternatives to Malcom Floyd.
Entering the 2012 season, San Diego was hoping Malcom Floyd was prepared to step up and take over the role vacated by Vincent Jackson.
Needless to say, it didn't turn out that way.
Floyd failed to post the 1,000-yard season San Diego was banking on. Instead, his yardage total actually went down from the previous season.
With Vincent Brown returning from injury and Keenan Allen in the fold after being selected in April's draft, the writing may be on the wall for Floyd if he doesn't up his game.
Floyd will count more than $8 million against the cap in 2014 and 2015. If he proves to be nothing more than a decent No. 3 wide receiver, especially with Brown and Allen in the fold, he'll likely be shown the door.
Kenny Britt needs to prove himself all over again.
This has more to do with an inability to stay on the field than an inability to actually produce when on the field.
Due to injury issues and off-field distractions, Kenny Britt has missed 19 games over the past three seasons.
Britt's rap sheet off the field includes arrests for providing false information, traffic violations, a hit-and-run, a DUI and a bar fight, per the Washington Post.
Needless to say, Britt needs to mature a great deal before the Tennessee Titans can rely on him to be the player they thought he'd be when they made him a first-round pick back in 2009.
When he's on the field, however, Britt has produced.
He is averaging 57 yards per game since the start of the 2010 season. Extrapolated over the course of a 16-game schedule, that equates to about 912 yards. Interestingly enough, that would have made Britt Tennessee's leading receiver last year.
Again, it is all about staying out of trouble off the field.
If Britt fails to do this, Tennessee will let him walk in free agency following the 2013 season.
Despite a pricy contact, Houston could have an out on Schaub following 2013.
When the Houston Texans signed Matt Schaub to a ridiculous five-year, $66.15 million contact, there were many who questioned the decision.
After all, Schaub had won a total of zero playoff games in five seasons as Houston's starting quarterback when the deal was announced last September.
The veteran quarterback responded to this big deal by having his worst statistical season since his first year as a starter for Houston back in 2007. His average yards per attempt, yards per completion and quarterback rating all dropped dramatically from previous seasons.
Houston would go on to win the AFC South and defeat the Cincinnati Bengals in the first round of the playoffs. However, it is important to note that Schaub didn't exactly set the world on fire in the postseason. Despite throwing for 343 yards against New England in the divisional round, Schaub threw an interception in Houston's lopsided 41-28 loss to Tom Brady and Co.
The veteran is nothing more than a decent game manager, which should be alarming for fans in Houston. Does Schaub have what it takes to go up against the Bradys and Mannings of the world in January and come away with a win?
If the answer is no, Houston might have to look in another direction following the 2013 season.
The issue with this is that about half of his 2014 contract is guaranteed, which puts the Texans in an unenviable position.
Either way, 2013 could be a make-or-break season for Schaub in Houston.
Miami selecting two corners in April surely put Richard Marshall on notice.
That makes him a marginal No. 1 cornerback on an average defense.
Unfortunately, Marshall missed all but four games this past season, his first with the Miami Dolphins. He recorded five passes defended and one interception in four starts.
The veteran corner is set to count more than $6 million against the cap in 2014. If Marshall fails to prove he can stay healthy and be productive, he'll likely be shown the door. After all, none of his 2014 salary is guaranteed.
Adding more fuel to the fire is the fact that Miami spent two rather early picks this past April on cornerbacks. It picked up Jamar Taylor in the second round before adding small-school stud Will Davis from Utah State in the third. Miami also signed former Pro Bowler Brent Grimes away from Atlanta in free agency.
If Taylor and Davis step up as rookies in 2013, Marshall will be looking for a new home come March.
It really is that simple.
Levi Brown has been an enigma since Arizona made him a first-round pick.
Levi Brown has yet to live up to the expectations that came with being selected No. 5 overall out of Penn State back in 2007.
He moved from right tackle to protecting the blindside following the 2009 season and things seemed to just remain stagnant. Arizona quarterbacks were sacked 50 times in Brown's first season at left tackle.
It shouldn't come as much of a surprise that he graded out as the worst pass-protecting offensive tackle in the entire league that season, according to Pro Football Focus (subscription required).
Fast forward a year and things weren't much better. Using the same grading system, Brown was the second-worst pass-protecting offensive tackle in 2011. It's not a coincidence that Arizona quarterbacks went down 54 times that season.
Brown now returns to left tackle after missing the entire 2012 season. He is going to be tasked with protecting an immobile Carson Palmer for a Cardinals offensive line that yielded a league-high 59 sacks last season.
Do you see a trend?
Fortunately for the Cardinals, they have a whole host of young offensive linemen ready to step up. Bobby Massie, who was selected in the fourth round of the 2012 NFL draft, impressed at right tackle as his rookie season went on. By the end of the year, Massie was one of the most surprising rookies in the entire league.
Fellow 2012 draft pick Nate Potter started six games at left tackle and actually had a better grade in pass protection than Brown had in his previous two seasons at that position.
Brown signed a new five-year, $30 million contract with Arizona last March. The deal called for $8 million guaranteed. This means that the Cardinals could release their former first-round pick without having to take on dead money after this season.
Even if he does make the 53-man roster and earns the starting left tackle job, Brown will need to impress in order to collect the $7.6 million he is set to earn in 2014.
Just two years removed from a Pro Bowl campaign, Rogers may not be guaranteed a roster spot.
When Carlos Rogers signed a one-year, $4.25 million contract with San Francisco prior to the 2011 season, there were many experts who believed he couldn't perform up to the level of Nate Clements, who he was tasked with replacing.
Rogers went on to earn a Pro Bowl appearance in his initial season with the 49ers. He recorded 19 passes defended and six interceptions that season.
That performance enabled Rogers to earn a four-year, $29.3 million contract prior to the start of last season. After all, he seemed to have taken that elusive step towards elite status.
However, Rogers wasn't able to continue that upward trend in 2012.
He recorded only one interception and six passes defended. Outside of basic statistics, Rogers finished up the 2012 season as San Francisco's third-best cover corner, via Pro Football Focus (subscription required).
With Chris Culliver and Tarell Brown stepping up last season, there were questions about whether Rogers would have a role on the 49ers this season.
Those questions were even more magnified when San Francisco brought in Nnamdi Asomugha in free agency.
While it is highly unlikely that Rogers becomes a training camp casualty, his role on the team in 2013 and beyond is up in the air.
The veteran is set to count over $17 million against the cap in 2014 and 2015. It's pretty obvious that Rogers' performance this past season coupled with his advanced age will lead to a release at some point in the not-so-distant future.
Williams' cap hit is lowered if he is released after '13 season.
Unfortunately for DeAngelo Williams, the Carolina Panthers seem to have gotten away from actually using him on a consistent basis.
The former first-round pick averaged 4.8 yards per rush over the past two seasons, but only carried the ball 10 times per game during that span.
Talk about not getting value.
Carolina signed Williams to a five-year, $43 million contract extension back in 2011. At that time, it was going to rely on him to be a workhorse.
Obviously, that hasn't panned out.
Williams did restructure his contract last month, which guaranteed him a spot on the roster this upcoming season. That being said, Carolina owes him nothing in guaranteed money beyond the 2013 season and could get out his deal.
Unless Williams accumulates more carries and his production returns to 2009 form, he will be looking for a new team next spring.
It remains to be seen if Will Smith fits Saints new defensive scheme.
I am intrigued to see how Will Smith fits into the Saints' new 3-4 defensive scheme. He will now be playing with his hands up at outside linebacker after lining up at defensive end in his first nine seasons with the team.
As evidenced by how poorly Dwight Freeney played after making that transition in Indianapolis last season, it's difficult to teach a old dog new tricks.
In addition, Smith has struggled to live up to rather high expectations over the past few seasons. After recording 13 sacks in 2009, Smith hasn't racked up more than 6.5 in any season since.
Smith, who has restructured his contract each of the last two offseasons, is set to count more than $13 million against the cap in 2014.
Short of proving he can actually make the transition and return to form, Smith will not be a part of the Saints' future plans on defense.
Could the Buccaneers really be looking to replace Freeman?
Many experts were caught off guard when Tampa Bay selected Mike Glennon in the third round of April's draft. For a team with a plethora of needs on both sides of the ball, it made little sense to exhaust a rather early-round pick on a backup quarterback.
Unfortunately for Josh Freeman, it appears that the Buccaneers selected Glennon as an alternative at the quarterback position.
General manager Mark Dominik even went as far to indicate that Glennon will get an extensive look during the preseason and training camp, per Pro Football Talk.
We’re going to put a lot of pressure on [Glennon] and see a lot of reps from him in the preseason. He’s got to play,” Dominik said. “We may not see as much of Dan Orlovsky or even of Josh Freeman somewhat in the preseason as much as you’re going to see Glennon.
While it would take a lot for Glennon to beat Freeman out in training camp, the writing might be on the wall here.
Freeman has continued to struggle with decision making and mistakes since a breakout 2010 campaign. He has thrown 39 interceptions over the last two seasons, which ranks him ahead of even Mark Sanchez during that span.
The Kansas State product is also set to become a free agent following the 2013 season. Some quarterback-needy team might end up overpaying for his talent, something I am sure Tampa Bay has taken into account.
Assuming Freeman wins the starting job, he'll need to improve dramatically from the past two seasons in order to remain in Tampa Bay beyond 2013.
Vincent Frank is an NFL featured columnist here at Bleacher Report. Vincent is the head sports editor over at eDraft, co-host of Draft Sports Radio, which airs every Monday and Wednesday from 3 to 6 p.m. ET, and a fantasy writer for Pro Football Focus.
Go ahead and give him a follow on Twitter @VincentFrankNFL.