The case of Justin Tuck is a curious one. Not long ago, the New York Giants defensive end was regarded as one of the league's best young stars. He was a highly decorated, championship-tested, high-talent, high-character player who was equally adept at terrorizing quarterbacks on Sundays and helping set the tone Tom Coughlin wanted in the locker room all week. In 2010, Tuck had 11.5 sacks for a Giants team that won 10 games but barely missed the playoffs. He was 27 when that season ended, and his future looked like one big trip around the sun.

But it has not been that. The past two seasons of Justin Tuck have been a mopey muddle -- a confusing blend of injuries, ineffectiveness and a surprising, self-acknowledged struggle with motivation. He needed a December 2011 pep talk from Coughlin to inspire him for the Giants' latest Super Bowl run. But other than the 5.5 sacks he had in that six-game stretch that included the final two regular-season games and four postseason games, Tuck has recorded a total of just seven over the past two seasons. In 21 of his past 31 games, Tuck has failed to record even a partial sack.

Now, this is a guy who just turned 30 a few weeks ago, so it's a bit of a leap to say for certain that he's "done." But I feel confident saying that 2013 is a very important year in Tuck's career. It is the final year of his current contract, which means he's literally playing for a job. The fact that the Giants haven't yet made a move to extend his deal tells you they have concerns about the type of player they can expect him to be. The pass rush is too important a part of what the Giants do for them to allow it to decay around one player, no matter how important a part of their championship history that player has been. If Tuck looks like his old self this year, rejuvenated and ready for a big next chapter in his career, the Giants will be thrilled to talk deal with him next offseason. But if 2013 is a repeat of Tuck's regular-season performances from 2011 and 2012, it's likely to be his final year as a Giant.

One of the fascinating things about this year's Giants, though, is that Tuck is not alone. All over the roster, you find players for whom 2013 could be the proverbial "make or break" year. Yes, they held up a Lombardi trophy just 15 months ago, but this team also has missed the playoffs in three of the past four seasons. So it's not a huge surprise that next offseason might find the Giants in a period of transition, with big decisions to be made on several of their core players:

CB Corey Webster: There was a chance he could have been gone this offseason after his disappointing 2012. Webster's decision to accept a significant pay cut extended his time in New York, but he's also entering the final year of his deal. And with Prince Amukamara and Jayron Hosley, the team has been thinking ahead for a while now about its defensive backfield of the future. Webster, now 31, would need a big bounce-back season if he wanted to be part of that future.

S Antrel Rolle: He'll be 31 when the season ends; he has two years left on the five-year free-agent deal he signed with New York before the 2010 season; and he's counting $9.25 million against the salary cap in each of those years. The Giants are swallowing that this year, but they're unlikely to want to commit that much to Rolle again in 2014, especially if he fails to replace Kenny Phillips as the leader of their secondary. Rolle's play dropped off last year when Phillips wasn't on the field, and he needs to show in 2013 that the contributions he made early in his Giants career weren't tied to the way he worked in tandem with Phillips.

G Chris Snee: A longtime pillar of New York's offensive line, Snee is 31 years old and has been banged-up and less effective the past two seasons. That's understandable, given the demands of his position and the dedicated way he plays it and plays hurt. But he also is signed through 2014, with a $7.5 million cap cost for that year. The Giants just used their first-round draft pick on an offensive lineman, Justin Pugh, who played tackle in college but could project as an NFL guard. Although it's easier to see Pugh's taking over for Kevin Boothe, who is signed only through this year, don't rule out his replacing Snee instead if Snee has a down season.

WR Victor Cruz: This assumes he and the Giants don't reach an agreement on a long-term deal and he plays out his contract on his restricted free-agent tender. That would make Cruz's season the ultimate make-or-break. Another monster production season like those he has had the past two years and he hits the open market with teams drooling over him. If he gets injured or has a drop-off in production, though, he'll wish he had taken what the Giants were offering this offseason.

WR Hakeem Nicks: Again, it's possible he'll sign for the long term before the season starts. But if not, this is the final year of his contract and he has to show he can stay healthy and deliver as the No. 1 receiver the Giants believe he is. His situation is tied to that of Cruz, and it's tough to find a scenario in which the team can keep both.

So 2013 is a big year for a lot of very familiar Giants faces. This franchise grooms replacements for its stars and major contributors very well, so turnover isn't a terrifying thing for the Giants. But it's possible that, even for them, next offseason could feel like a real changing of the guard in some key spots.