So much can change over the course of one MLB season. Players with expiring contracts and those coming off uncharacteristically strong or poor performances have the most to gain and lose in 2013.
We can only observe results. Therefore, it's the responsibility of those individuals to make subtle changes in their preparation to ensure that everything goes smoothly under the bright lights.
Avoiding injury is also particularly important for the following guys. If a player needs to rebound from a lost season, he'll want every opportunity to prove that it was a fluke. Likewise, hot commodities could suffer financial losses if they can't validate a breakout year.
The baseball world will certainly be keeping a close eye on these men.
Like many others on this list, Phil Hughes is eligible for free agency following the 2013 season and is looking to cash in.
The right-hander has always had trouble keeping balls in the yard and pitching into the later innings. Even if he doesn't improve, he's probably in line for a two-year, $20 million contract.
However, he could ink a much longer guarantee by showing better control of his filthy curveball.
While it's good that Hunter Pence emerged as a leader with the San Francisco Giants and played regularly during their World Series run, he struggled at the plate. His .219/.287/.384 triple-slash line with them in the regular season dipped to .210/.231/.290 in the playoffs.
Pence's salary could approach $14 million in his final year of arbitration eligibility. He won't do nearly as well on his next contract if the slump persists.
Bonderman hasn't pitched in the majors since 2010.
It's very likely that Jeremy Bonderman will pitch for the Seattle Mariners in 2013. Their rotation lacks depth behind Felix Hernandez and Hisashi Iwakuma as the top prospects continue to develop.
Bonderman hasn't pitched in the majors since 2010, but elbow surgery and better conditioning should help him regain velocity.
FanGraphs shows us that the right-hander gradually lost confidence in his changeup. He must refine and use that third pitch to make this comeback successful.
Was Ruggiano's 2012 performance a fluke?
Justin Ruggiano was initially sent to Tampa Bay in 2006 as the player to be named later in a low-key trade. He didn't show much upside during five-and-a-half years in the organization, so the Rays let him go when he refused a minor league assignment.
Receiving regular starts with the Miami Marlins last season, Ruggiano posted excellent offensive numbers. The sample size was just 320 plate appearances, but his .909 OPS nearly matched those of stars like Adrian Beltre and Aramis Ramirez.
He become eligible for arbitration in the winter, and the Fish wonder whether he's really an everyday outfielder or a flash in the pan who began coming back down to Earth in September.
The Boston Red Sox named Joel Hanrahan their closer as soon as the acquisition became official.
However, they have a couple strong alternatives to move up in the pecking order should he falter. Andrew Bailey excelled during his time with the Oakland Athletics, and newly signed Koji Uehara pitches with pinpoint control.
The 31-year-old Hanrahan blamed his second-half control problems—18 walks, four wild pitches in 25.2 innings pitched—on ankle and hamstring issues (via Evan Drellich, MLB.com).
For his sake, that better be the truth. If the wildness persists, there won't be many suitors trying to sign him next offseason.
Last summer with the Milwaukee Brewers, Francisco Rodriguez was overused and unsuccessful.
Reduced velocity from his first few years in the league means that he'll never enjoy an off-the-charts strikeout rate again. Still, K-Rod can average about one punchout per inning pitched.
In September 2012, this former closer proved that he can thrive in a setup role. Through the end of this decade, there should be teams signing him to major league deals.
It's up to Rodriguez, though, to restore his reputation as much as possible and reenter free agency as a hotter commodity.
Ricky Nolasco allowed 244 hits in 2011—the most in the National League. He would've earned that distinction again in 2012 had he made a couple more starts.
The impending free agent looked like an ace when he first became a full-time rotation member, but his strikeout rate is nowhere near where it ought to be.
Nolasco still has an excellent speed differential between his fastball and curve. It's unfortunate that he can't use those weapons to miss more bats.
This regressing right-hander needs to locate pitches on the borders of the strike zone rather than down the middle. Otherwise, he won't make an $11.5 million salary again.
Banned for 25 games after testing positive for amphetamines, Carlos Ruiz has an abbreviated season with which to restore his reputation.
He'll earn $5 million in 2013 and then hit the open market.
Scott Baker has put himself in a good situation. He's guaranteed $5.5 million coming off a year when he didn't pitch and is now in the National League Central, arguably baseball's least-improved division this offseason.
A starter at his age (31) with such a solid strikeout-to-walk ratio (3.44) will be coveted in the future regardless. But improving upon his 2011 stats could vault him into a higher tier.
A perennial NL All-Star before hurting his shoulder, Brian McCann will be the top catcher available in free agency following the World Series.
It's imperative that he doesn't rush back from October surgery. Doctors originally estimated that recovery would cost him a small portion of the 2013 season.
McCann used to be a middle-of-the-order producer at a premium defensive position, with a .286/.358/.486 career triple-slash line through 2011. But he was physically limited last year, batting .230/.300/.399 and amassing only 487 plate appearances.
Kevin Burkhardt of SportsNet New York reports that the New York Mets have interest in Grady Sizemore.
Once a durable superstar center fielder, the 30-year-old's career has recently been derailed by a rash of injuries. He signed a major league deal with the Cleveland Indians last year but never played a game.
As he heals from microfracture knee surgery, Sizemore just wants the opportunity to play again. It's doubtful that anybody would contact him next offseason unless he gets back on the field at some point in 2013.
Chamberlain looked like his old, dominant self in September.
Joba Chamberlain caught everybody's attention during his first couple MLB seasons. His high-90s fastball and devastating slider were close to untouchable.
But a few years later, the fireballer who was destined to lead the New York Yankees rotation is just a middle reliever.
Chamberlain heads toward 2013 as an impending free agent. Though a starting job is no longer realistic, renewed dominance would make him a strong candidate to replace the legendary Mariano Rivera or find closer's work elsewhere.
We can tell from Baseball-Reference.com that Kris Medlen's surreal stint in the Atlanta Braves' starting rotation won't be emulated.
This a what-have-you-done-for-me-lately kind of sport. Medlen could come crashing down from his pedestal awfully fast.
Regression is inevitable for Fernando Rodney too. He posted a 0.60 earned run average a season ago, the lowest ever by an MLB reliever.
Balls in play are out of his control, but Rodney can still be elite if he replicates last season's walk rate. He was better than average in that department for the first time in his career.
Continued dominance should earn him a multi-year free-agent contract with at least $10 million guaranteed.
Miami Marlins manager Ozzie Guillen kept Heath Bell in the closer's role for half a season despite his ineffectiveness. There just weren't many better options in that bullpen.
Bell is expected to begin 2013 in a setup role with the Arizona Diamondbacks. They have enough depth to bury him in the pecking order or even designate him for assignment. Hopefully, such threats motivate the 35-year-old to hone his skills.
The Chicago Cubs clearly intend to dismantle their starting rotation at midseason again. Edwin Jackson is obviously staying put, but they hope Matt Garza—coming off an elbow injury—will restore his trade value in the first few months of 2013.
A move would be in his best interest too. The right-hander is extremely competitive and undoubtedly misses the postseason after qualifying for it twice while with the Tampa Bay Rays.
Even if Garza gets going slowly, he'll be looking to sign a hefty guarantee in the offseason.
He last pitched on July 21.
Ryan Madson injured his elbow during spring training and underwent Tommy John surgery.
He has since signed a one-year, incentive-laden deal with the Los Angeles Angels. The 32-year-old will pitch in pressure situations as the team's closer.
Coming off a strong season with the Philadelphia Phillies in 2011, Madson nearly re-signed for $44 million. Another masterful campaign could put him in that position once again.
Tommy Hanson has steadily slumped since his terrific MLB debut in 2009. It will be tough to buck the trend next season as he transitions to the American League.
No more opposing pitchers to make easy outs at the plate. Also, the overall quality of the Los Angeles Angels defense doesn't match Atlanta's.
Hanson could be a non-tender candidate if he continues to underwhelm.
Best-case scenario? He emerges as a solid No. 3 starter.
C.J. Wilson's debut season on the West Coast deteriorated after the All-Star break. He allowed more baserunners as the summer wore on and couldn't keep balls in the ballpark.
His $77.5 million contract is heavily back-loaded. Conveniently, full no-trade protection is limited to eight teams beginning next winter.
The Los Angeles Angels already have Josh Hamilton, Albert Pujols and Jered Weaver on the payroll for years to come, not to mention Erick Aybar, Chris Iannetta and Howard Kendrick.
Without an immediate return to his Texas Rangers form, Wilson could be off the team and possibly dealt across town to the Los Angeles Dodgers. They don't mind overpaying for mediocrity.
Phillies general manager Ruben Amaro Jr. tells Corey Seidman of CSNPhilly.com that he's only "cautiously optimistic" that Chase Utley can be an everyday player.
For those who may have overlooked him, this second baseman used to be in very elite company, as Bleacher Report Lead Writer Zachary D. Rymer tweeted about his sabermetric excellence.
Though limited by knee problems in recent seasons, Utley has been a terrific defensive player.
With his contract running out, he could return to grandeur, disappear on the bench or be anywhere in between.
Incumbent center fielder Michael Brantley shifts over to left to accommodate Drew Stubbs. These players are at similar stages of their careers, but trending in opposite directions.
Stubbs strikes out more often than any athletic player should and doesn't draw enough walks to utilize his base-stealing ability.
Even the lowly Cleveland Indians cannot retain a multimillion-dollar player with a .277 on-base percentage. He'll be non-tendered if that's how he performs next season.
On the other hand, Stubbs seemed to be the next coming of Grady Sizemore after his 2010 campaign. One would believe that he still has that potential.
WAR measured by both Baseball-Reference.com and FanGraphs agree that Michael Young really struggled in 2012.
The 36-year-old is now in the National League, adjusting to new rules and unfamiliar opposition.
His next contract will surely pay less than his expiring five-year, $80 million deal. At this rate of decline, Young won't get a starting job anywhere in the future.
Talent has taken Edinson Volquez this far, but it won't get him another starting job in Major League Baseball.
Among active starting pitchers (min. 500 IP), only Jonathan Sanchez carries a higher career walk rate.
Luckily for Volquez, he's currently on the San Diego Padres. They are reluctant to spend on reputable rotation candidates (who would push him down the depth chart).
The bad news? Petco Park is moving in its fences for the 2013 season.
The right-hander needs to make significant adjustments in his walk year.
Fortunately, Ricky Romero is under contract for another three seasons. However, if the 2013 version resembles last season's incompetent starter, he'll be sent to the bullpen or to a non-contender south of the border.
The Toronto Blue Jays have spent lavishly to improve, and Romero is clearly slotted in the No. 5 rotation spot.
Even with a new coaching staff in place, the former first-round pick will need to work his way out of the doghouse.
Jorge De La Rosa.
The Colorado Rockies will likely exercise their $11 million club option on Jorge De La Rosa for the 2014 season if he's healthy and reasonable effective.
He made only three starts last season following Tommy John surgery and didn't fare well. Moreover, the right-hander has surpassed 130 innings pitched only once in his MLB career.
The high altitude of Coors Field always cripples pitching stats, so De La Rosa might be undervalued on the free-agent market unless he performs better than ever.
Kendrys Morales was protected from left-handed pitching last season, totaling only 76 of 522 plate appearances against southpaws.
With the Seattle Mariners, however, he'll be an everyday player.
Can Morales return to the 2009 version of himself who finished fifth in AL MVP voting? Or will the league expose him as a platoon guy?
That difference could be worth tens of millions of dollars to the impending free agent.
Before suffering a torn flexor tendon in his elbow, Colby Lewis was on track for a nice, multi-year deal in free agency.
The uncertainty of the injury led him to accept an extension from the Texas Rangers. He'll earn a $2 million base salary next season, with another $4 million available in performance bonuses.
Lewis, who once reached the 200-inning mark in consecutive campaigns, is reportedly ahead of schedule in rehab. The Rangers feared it would take him a full year to get back on the 25-man roster, but Gerry Fraley of the Dallas Morning News writes that he could return in May.
The 33-year-old can be more effective than ever if he stops relying on fly balls. Since returning to Major League Baseball in 2010, Lewis has surrendered one home run about every seven innings.
The Boston Red Sox have shortstop prospects Xander Bogaerts and Jose Iglesias, so Stephen Drew is unlikely to return after his one-year deal expires.
Next season, he wants to prove himself worthy of being a long-term starter elsewhere. Matching his averages from 2008-2010—16 HR, .800 OPS, 146 G—would suffice.
Likewise, Dan Haren settled for a "pillow contract" this winter. He found a temporary landing spot following a disappointing year and expects to receive bigger offers next time around.
In a typical year, the right-hander throws 215-plus innings while maintaining a sub-4.00 earned run average. Doing that again would make Haren a very attractive free agent.
The concern is that chronic back and/or hip issues affect his mechanics and prevent him from being the durable starter he used to be.
The Garrett Jones/Gaby Sanchez platoon is going to cost the Pittsburgh Pirates $6.2 million in 2013, according to MLB Trade Rumors. That price will rise further in the coming years as both pass through arbitration.
This small-market club could soon come up with another solution at first base and acquire one player with more even platoon splits.
Sanchez is the cheaper player but is coming off a much weaker season. Despite being a 2011 NL All-Star, the 29-year-old will begin the journeyman phase of his career if he fails to produce more at the plate.
Is A.J. Burnett actually an elite pitcher after an awful tenure with the New York Yankees?
Don't believe it until you see him do it again. Another strong season at age 36 should get him a multi-year deal.
Carlos Gomez has always been a great defensive center fielder. In 2012, he enjoyed a breakout year with the bat, slugging 19 home runs in only 415 at-bats.
The 27-year-old wants to compete with Jacoby Ellsbury—a fellow Scott Boras client—for the largest contract among free-agent center fielders. If this power is legitimate, he will have similar qualifications.
But Gomez can't get a mega deal unless he learns better plate discipline. His lifetime .294 on-base percentage is unacceptable for a top-of-the-order speedster.
Take more pitches or take fewer years.
Roy Halladay spent six consecutive summers in Cy Young contention but wasn't anywhere near the conversation in 2012.
His legacy is safe. The right-hander is a Hall of Famer if he retires today. But following a year in which he barely pitched above replacement level, Halladay has plenty to gain (including a lucrative contract extension).
Mike Trout is already atop the baseball world. Fantasy league addicts and traditionalists alike seem to be in awe of his stats and hustle, respectively.
He can only go down from here, but it's a long way down.
Trout and the aforementioned Kris Medlen are in a similar spot. Because "Wonderboy" dominated over a five-month stretch and did so at such a young age, he has more at stake.
Robinson Cano is the best second baseman of his generation because he combines unbelievable offensive skills with smooth defense. The fact that he has averaged 160 games played per season since 2007 makes him even more desirable.
He could negotiate for an Albert Pujols-like contract next winter if he completes the leap from most valuable infielder to AL MVP in 2013.
Johan Santana has a streak of his own, which, unfortunately, is still intact. He has spent time on the disabled list in each of the past four seasons.
His $25 million club option for 2014 will not be picked up.
Santana will be hard pressed to secure a multi-year deal unless he snaps out of his post-no-hitter funk. Sustaining the quality of his work from the first couple months of 2012, meanwhile, would draw interest from all 30 teams.
Barry Zito is what he is: a soft-throwing southpaw who serves as an adequate back-end starter when he pitches in large ballparks.
He'll make $20 million in the final guaranteed year of his contract.
However, if Zito can pitch efficiently and log at least 216 innings next season (a total he hasn't reached since 2006), an $18 million option automatically vests. The San Francisco Giants might even reward his workhorse performance with a contract extension.
In the more realistic scenario, he pitches relatively short outings, which means the Giants get to decide between the expensive option and a $7 million buyout. The latter is the obvious choice.
Johnson is pitching in the American League for the first time.
Josh Johnson and his agent are "open"—you could even say eager—to sign a contract extension, reports Brendan Kennedy of the Toronto Star.
The Toronto Blue Jays haven't exactly reciprocated that desire.
Though talented, the well-built right-hander lacks durability. He was also missing some zip on his fastball in 2012.
Despite the current doubts, ESPN Insider Buster Olney explains that a steady season would position him to "cash in big."
In all likelihood, Jacoby Ellsbury peaked in 2011.
Much like Joe Mauer two years prior, he will probably never hit 30-plus home runs again or lead the American League in total bases.
At the very least, this center fielder wants to prove that his body can last an entire season. That historic year is sandwiched between a couple injury-prone campaigns.
Moreover, Ellsbury was very pedestrian for the 2012 Boston Red Sox when healthy (.271/.313/.370 in 323 PA).
The 29-year-old has his work cut out for him, but so much to gain.
During the regular season, the San Francisco Giants would've been better off without Tim Lincecum.
Though his pitch selection hadn't changed, his mechanics did. Lincecum's velocity and location suffered as a result.
The former NL Cy Young Award winner flourished in the playoffs out of the bullpen. It remains to be seen, however, if he can work well out of the windup once more.
His free-agent value hangs in the balance.