For a number of reasons -- chief among them the freak nature of his 2012 season-ending injury, the concern it could be career-ending and the noticeable absence of "Enter Sandman" last October -- Mariano Rivera's expected return to the mound figures to be one of the main storylines in the early portion of the upcoming season.

Yet there are plenty of other key players who missed most, if not all, of last season, who might be worth keeping an eye on in 2013. Victor Martinez, John Lackey, Logan Morrison, Scott Sizemore and Wilson Ramos were among the notable players mostly absent from play last summer, along with a string of Rivera's fellow closers, including Ryan Madson, Joakim Soria, Sergio Santos and Brian Wilson.

Of the five closers, Rivera appears to be the only one who will immediately step back into his previous role for the same team with which he started last season.

"Like I've been saying, I didn't want to go out like that," said Rivera, who tore his right anterior cruciate ligament on May 3 while shagging fly balls during batting practice. "I didn't want that to be the last image. But it wasn't an easy decision, because there's more than just baseball with me."

The decision may have been easier knowing he'll instantly reassume his long-time closer role, something that can't be said for the other closers bitten by last year's injury bug.

Santos, who made just six appearances with the Blue Jays after being acquired from the White Sox last winter, is the only other one still under contract with the same team. As for his role in the immediate future, the 29-year-old reliever could assume the closer duties if he reports to camp healthy and impresses, but he won't be guaranteed the spot.

Madson, meanwhile, was fortunate enough to sign with and expects to close for the Angels, and Soria appears headed for a setup role with the Rangers once he returns to full health. Wilson remains a free agent, despite averaging nearly 41 saves from 2008-11 before making just two appearances prior to undergoing Tommy John surgery last year.

Madson also went under the knife for Tommy John surgery last year, failing to record a single appearance after joining the Reds. Prior to signing with Cincinnati, the right-hander had spent each of his first nine big league seasons with the Phillies, where he racked up a 3.60 ERA, including a 2.89 mark in his last five seasons in Philadelphia.

"If Ryan Madson is throwing the ball like he has over the course of his time in the big leagues, and particularly the last five years before Tommy John," said Angels general manager Jerry DiPoto, "he's one of the premier relievers in the game."

That potential return to form is something the Angels are hoping will help serve as the answer to their bullpen struggles from a season ago. As for Wilson, the fellow Tommy John patient hasn't been fortunate enough to receive such an opportunity quite yet.

Part of the reason the Giants have been reluctant to bring back Wilson is the obvious success of the team during Wilson's absence. Sergio Romo recorded four postseason saves to go along with a 0.84 ERA en route to the Giants' World Series title last season. The right-hander has also posted a combined 1.65 ERA over 134 regular season appearances the last two years.

Another concern is the fact this was Wilson's second Tommy John surgery and there is no guarantee he'll be ready come Opening Day.

"I think anybody who signs Brian, whether it's us or somebody else, will have to take into account that you have to do what's best for the player," Giants vice president of baseball operations Bobby Evans said at last month's Winter Meetings. "Even though it may be ideal to have him out there to start the season, you have to prepare for him not to be out there because that may be in his best interest."

Though the Tigers also reached the Fall Classic while playing the entire season without one of their stars, they are ready to welcome back Martinez with open arms.

Like Wilson, Martinez has a few red flags accompanying his return -- considering he's 34 years old and recovering from extensive surgery to his left knee -- but he has the luxury of not needing to play defense by serving as the Tigers' designated hitter.

What type of production Martinez provides remains to be seen, but adding a .303 career hitter to a lineup that already features Triple Crown winner Miguel Cabrera and Prince Fielder is certainly a welcomed treat for the defending American League champions.

Not everyone who missed most of last season will be returning to such a pleasant situation, though.

Take Red Sox starter Lackey, who completely missed out on the Bobby Valentine era in Boston. After missing all of last season following Tommy John surgery, Lackey will return to Boston's rotation in the wake of the club's last-place finish in the AL East that led to Valentine's dismissal.

Morrison will return to a completely different team than the one he left in Miami. Since Morrison's season ended on July 28 last year, the Marlins have fired manager Ozzie Guillen, flipped almost their entire starting lineup and plan to move Morrison from left field to first base. Besides Morrison, only Giancarlo Stanton remains from last year's Opening Day starting lineup.

Then there are the players like Rivera's teammate Michael Pineda, whose status for the upcoming season remains unknown, though he optimistically is hoping to return by the end of August.

Regardless of the circumstances surrounding last year's injuries and whether this season is just the next chance (for guys like Madson) or the final chance (for a guy like Rivera), there's one common thread shared by everyone returning to the diamond in 2013.

"I'm not just coming back to play," Rivera said after signing his one-year contract. "I'm coming back to win."