MLB teams ideally have a mix of productive veterans, well-developed prospects and elite players in their prime years. That kind of overall age profile all but assures contention.
Each slide caption begins with individuals expected to spend most of the season on active rosters. They are categorized as either "young impact players" (25 years or under as of Apr. 1, Opening Day) or "old impact players" (35 years or above as of Apr. 1).
Clubs with more names in the latter group understandably didn't do well in these rankings (e.g. the New York Yankees). Athleticism, bat speed and velocity are all declining for players in their mid-30s. Despite the intangibles that those elder statesmen provide, they are often less valuable on the field and more susceptible to serious injuries.
Those with the "best" age profiles can sustain their level of performance throughout 2013 or even improve as the months pass without acquiring players from outside the organization.
*Asterisks indicate players expected to begin the regular season on the disabled list.
Derek Jeter injured his ankle in October and hasn't fully recovered.
Young impact players: IF/OF Eduardo Nunez.
Old impact players: SS Derek Jeter, DH Travis Hafner, RHP Hiroki Kuroda, LHP Andy Pettitte, RHP Mariano Rivera, 3B Alex Rodriguez*, RF Ichiro Suzuki, 1B Mark Teixeira*.
After being baseball's oldest team in 2012, the New York Yankees decided to re-sign several of their geezers. Once again, Kuroda, Pettitte and Suzuki project to get a lot of usage.
New lineup additions Travis Hafner and Kevin Youkilis aren't noticeably declining (ages 36 and 34, respectively).
On the other side of the spectrum, N.Y. is lacking MLB-ready talent in the high minors. Catcher Austin Romine has already been removed from camp, while prized right-hander Manny Banuelos underwent Tommy John surgery in October.
Due to significant injuries and lack of depth, many experts expect the Yankees to miss the postseason for the first time since 2008.
Juan Pierre is way past his prime.
Young impact players: RHP Henderson Alvarez, C Rob Brantly, RHP Nathan Eovaldi, SS Adeiny Hechavarria, 1B/LF Logan Morrison, 2B Donovan Solano, RF Giancarlo Stanton, RHP Jacob Turner.
Old impact players: LF Juan Pierre, 3B Placido Polanco.
Youth is good in moderation, but the Miami Marlins went too far.
Of the above youngsters, only Stanton has established himself as an above-average player. Eovaldi and Turner have never come close to pitching 200 innings in a single summer, so they are vulnerable to fatigue in 2013.
However, Miami can look forward to promoting a lot of young talent in the near future.
None of the middle-aged Marlins—like Ricky Nolasco and Justin Ruggiano—have been consistent from year to year. It's all but assured that the former, an impending free agent, will find a new home this winter.
Young impact players: 2B Jose Altuve, C Jason Castro, 3B Matt Dominguez, OF J.D. Martinez.
Old impact players: none.
The rebuilding Houston Astros brought in several inexpensive veterans: Rick Ankiel, Erik Bedard, Carlos Pena and Jose Veras. None of them, unfortunately, have shown much consistency in recent campaigns.
The farm system is richer in quantity than quality. Most of Houston's early-round draft picks in recent years have been selected from high schools, and it's too soon to tell whether they'll be effective in the majors.
Phil Humber, Justin Maxwell, Brett Wallace and others in their prime years have produced mixed results in limited MLB experience.
Jimmy Rollins and Chase Utley.
Young impact players: OF Domonic Brown, IF Freddy Galvis, CF Ben Revere.
Old impact players: RHP Chad Durbin, RHP Roy Halladay, 3B Michael Young.
Mike Adams, Cliff Lee, Carlos Ruiz and three-quarters of the Philadelphia Phillies infield just missed the "old impact players" cut-off.
For the second straight year, the team has an ordinary bench and few capable farmhands, so just a few injuries could be crippling.
Young impact players: LHP Felix Doubront, 3B Will Middlebrooks.
Old impact players: RHP Ryan Dempster, DH David Ortiz*, C David Ross, RHP Koji Uehara.
The Boston Red Sox strengthened their club in free agency but dramatically weakened their age profile in the process.
For one, they re-signed Big Papi just prior to his 37th birthday, even though he was still injured (Achilles)! Dempster had a disappointing stint with the Texas Rangers to end 2012, while Uehara—though untouchable at times—has averaged barely 48 innings pitched per season since 2010.
To counteract that, Boston has a handful of advanced prospects flaunting their skills this spring, including Xander Bogaerts, Jackie Bradley and Allen Webster. They could each earn a call-up in the coming months.
Young impact players: 1B Yonder Alonso, 3B/2B Jedd Gyorko, CF Cameron Maybin.
Old impact players: OF/1B Mark Kotsay.
The San Diego Padres skew a bit too far toward the young end of the age spectrum.
As a result, it's unclear what they should expect from some of their regulars.
Chase Headley and Cameron Maybin, for example, saw their OPS vary dramatically from 2011 to 2012. Which stats were more legitimate?
Their limited MLB experience makes that a difficult question to answer.
Milwaukee wishes Wily Peralta was more experienced.
Young impact players: RHP Wily Peralta, SS Jean Segura.
Old impact players: SS/1B Alex Gonzalez.
Contenders for spots at the back end of the Milwaukee Brewers rotation are too young, as none of them have pitched the equivalent of a full major league season.
The reserve outfielders aren't trustworthy, either. Of course, they won't likely see the field often behind Norichika Aoki, Ryan Braun and Carlos Gomez.
Milwaukee's bullpen composition is ideal with a mean age just below 30.
Young impact players: SS Dee Gordon.
Old impact players: 2B Mark Ellis, IF Jerry Hairston, IF Nick Punto, RHP Ted Lilly*.
The Los Angeles Dodgers could have filled a city bus with all the prospects they traded away last summer. Depth is a concern everywhere outside the starting rotation.
Gordon, the lone young infielder, is a shaky replacement for Hanley Ramirez, who's probably DL-bound with a thumb injury.
L.A. would be in dire straits if one of the graybeard utility guys got hurt early on.
Young impact players: 3B Brett Lawrie*.
Old impact players: IF/OF Mark DeRosa, RHP R.A. Dickey, LHP Darren Oliver.
Mark Buehrle is viewed as the most dependable cog in the Toronto Blue Jays starting rotation. Keep in mind, though, that he recently turned 34.
The other aforementioned veterans will be heavily relied on. DeRosa is being considered for everyday duty at third base should Lawrie miss Opening Day.
Young impact players: LF Starling Marte.
Old impact players: RHP A.J. Burnett, RHP Jason Grilli, IF John McDonald.
A.J. Burnett has evaded arm injuries for many years. At age 36, perhaps this is the summer his body finally betrays him.
The Pittsburgh Pirates have several rotation candidates to turn to in that scenario, though all are a bit immature.
By every measure (including age profile), new catcher Russell Martin is an upgrade behind the plate over Rod Barajas.
LaTroy Hawkins hasn't reached 60 innings pitched since 2009.
Young impact players: RHP Matt Harvey, SS Ruben Tejada, IF/OF Jordany Valdespin.
Old impact players: OF Marlon Byrd, RHP LaTroy Hawkins.
The New York Mets have a couple exciting options at Triple-A: catcher Travis d'Arnaud and right-hander Zack Wheeler.
But this team will be forced into the veteran free-agent market to replace an injured corner infielder or underachieving reliever.
At 34, Johan Santana is no longer the undisputed rotation leader.
Young impact players: RHP Trevor Cahill, CF Adam Eaton, 1B Paul Goldschmidt.
Old impact players: RHP Heath Bell, IF Willie Bloomquist, 3B Eric Chavez, RHP J.J. Putz.
There is simply too many elderly pieces on this Arizona Diamondbacks squad.
On the bright side, the starting rotation is built to handle an 162-game workload (everybody under 30).
Young impact players: OF Mike Trout.
Old impact players: LHP Scott Downs.
Trout single-handedly elevates the Los Angeles Angels to the No. 17 position in these rankings. Otherwise, the team's utter lack of MLB-ready farmhands would have dropped them into the 20s.
Going strictly by the birth certificate, L.A. would be optimistic about ace Jered Weaver. However, there has been a steady drop in his velocity since 2010.
Young impact players: 3B Manny Machado, RHP Chris Tillman.
Old impact players: RHP Luis Ayala, 2B Brian Roberts.
After spending so much time on the sidelines, 35-year-old Roberts won't necessarily solidify second base for the Baltimore Orioles.
Luckily, Alexi Casilla and Ryan Flaherty are capable substitutes.
More veterans on the bench would have helped the O's ascend to a higher spot in these rankings.
Young impact players: SS Elvis Andrus, RHP Neftali Feliz*, LHP Robbie Ross.
Old impact players: DH Lance Berkman, RHP Joe Nathan, C A.J. Pierzynski.
Derek Lowe has great odds of becoming the fourth player on the Texas Rangers with at least 35 years of life experience.
That isn't ideal.
Later in the season, though, youthful pitching reinforcements like Feliz, Martin Perez and Joakim Soria could improve this team's outlook.
Young impact players: CF Aaron Hicks.
Old impact players: IF Jamey Carroll.
This is perhaps the only league-wide rankings article you'll see in 2013 that has the Minnesota Twins in the middle of the pack.
Elderly middle infielders—in this case, Carroll—really affect a team's position.
The Twins compensate with a pitching staff full of men born in the 1980s.
Young impact players: LHP Madison Bumgarner, C Buster Posey.
Old impact players: 2B Marco Scutaro, RHP Ryan Vogelsong.
As was the case for the Los Angeles Angels, the San Francisco Giants don't have many viable options at Double-A and Triple-A, so injuries will hit them particularly hard.
But there's plenty to like about the age profile of the defending world champs.
Pivotal players like Matt Cain, Tim Lincecum, Buster Posey and Pablo Sandoval have time until their 30th birthdays.
Their most questionable offseason decision was re-signing Scutaro (birthdate: Oct. 30, 1975) for three years.
Detroit is reluctant to fully trust Bruce Rondon.
Young impact players: RHP Bruce Rondon.
Old impact players: RHP Joaquin Benoit, RHP Octavio Dotel, RF Torii Hunter.
The Detroit Tigers have optimal age variance among position players. Their outfield depth is especially impressive, as Nick Castellanos and Avisail Garcia wait for opportunities.
If the bullpen wasn't such a mess (rookie closer), the Tigers would have earned a top-10 spot.
Young impact players: LHP Jose Quintana, RHP Addison Reed, LHP Chris Sale, LF Dayan Viciedo.
Old impact players: 1B Paul Konerko, OF Dewayne Wise.
Konerko and Wise are definitely assets to the organization. Despite their age, each has great familiarity with the Chicago White Sox.
Actually, Quintana and Sale should be under the microscope coming off seasons where they shouldered unprecedented workloads as starting pitchers.
Young impact players: 2B Jason Kipnis.
Old impact players: 1B/DH Jason Giambi.
The agreements with Michael Bourn and Nick Swisher will probably be hindrances toward the middle of the decade.
But as of 2013, they provide a much-needed age infusion to a once-laughable Cleveland Indians lineup. Signing Brett Myers and Mark Reynolds had a similar benefit to the Tribe.
Young impact players: RHP Lance Lynn, SS Pete Kozma, RHP Trevor Rosenthal.
Old impact players: RF Carlos Beltran, LHP Randy Choate.
It's still the preseason and the St. Louis Cardinals already know that Chris Carpenter and Rafael Furcal—two projected starters—won't participate this season.
Young depth will help them endure those disappointing losses.
The St. Louis bullpen, the team's chief weakness not too long ago, is beautifully configured entering 2013. Most of the relievers split the age difference between Rosenthal (22) and Choate (37).
Young impact players: RHP Jhoulys Chacin, C Wilin Rosario.
Old impact players: RHP Rafael Betancourt, 1B Todd Helton, C Ramon Hernandez.
The Colorado Rockies, of course, faded early in the 2012 pennant race when the injury bug plagued their starting rotation.
But commend them for assigning aging team members to the bench and late-inning relief corps is generally a winning formula.
Ideally, they could have acquired a first baseman to push Helton further down the depth chart. Tyler Colvin, however, is emerging as a viable option at that position.
Young impact players: C Welington Castillo, SS Starlin Castro, 1B Anthony Rizzo.
Old impact players: LF Alfonso Soriano.
By 2015, the Chicago Cubs might sit atop a list like this. Soriano will be elsewhere by then, either retired or battling for a roster spot with one of 29 other teams.
Their infield (with the exception of third base) is already set for the next several years. It's just a matter of time outfielders Brett Jackson and Jorge Soler break through to the big leagues, too.
The front office pursued reasonably-aged free agents this past winter, all of whom should be productive in 2013.
Ryan Roberts and Jose Molina are both past 30.
Young impact players: LHP Matt Moore.
Old impact players: RHP Kyle Farnsworth, C Jose Molina, RHP Joel Peralta, RHP Fernando Rodney.
Tampa Bay Rays manager Joe Maddon might make frequent tweaks to his lineup, but not because he's concerned with keeping players rested. Aside from Molina, none of the batters have turned 35 yet.
James Loney, for example, might turn out to be a counterproductive signing, while Yunel Escobar is a potential disciplinary concern, but at least the Rays can trust their durability.
Jeff Niemann is the lone starting rotation member to recently serve a lengthy stint on the disabled list. Of course, don't expect a comebacker to fracture his leg again.
Young impact players: 2B Dustin Ackley, DH Jesus Montero.
Old impact players: LF/DH Raul Ibanez.
Aside from Felix Hernandez and Joe Saunders, it's uncertain whether any other Seattle Mariners starting pitchers will last for 30-plus turns of the rotation.
Not a problem. Danny Hultzen, James Paxton and Taijuan Walker—all highly-touted prospects—will soon be chomping at the bit to debut in the majors.
The front office wisely added age to a club that finished in the AL West cellar last year.
Young impact players: LHP Brett Anderson, RHP Jarrod Parker, RF Josh Reddick, RHP Dan Straily.
Old impact players: RHP Grant Balfour*, RHP Bartolo Colon*.
The young no-names who comprised the Oakland Athletics starting rotation in 2012 are now wiser and more confident.
Several infield position battles remain unresolved, but the club has a surplus of options.
The A's ought to be just fine provided that Balfour (knee surgery) and Colon (PED suspension) return in April as scheduled.
Young impact players: 2B Danny Espinosa, LF Bryce Harper, RHP Stephen Strasburg.
Old impact players: none.
Not a single soul on the projected Washington Nationals active roster is above the age of 33.
Moreover, their likely WAR leaders—Ian Desmond, Gio Gonzalez, Harper and Strasburg—haven't even peaked as professional players.
As accomplished veterans, Dan Haren and Rafael Soriano will provide great insight. Still, this group lacks a prototypical graybeard.
Young impact players: LHP Tim Collins, RHP Kelvin Herrera, 1B Eric Hosmer, 3B Mike Moustakas, C Salvador Perez.
Old impact players: LHP Bruce Chen.
The Kansas City Royals age distribution nearly mirrors that of the Washington Nationals.
Chen, despite his mediocrity over the past calendar year, propels K.C. one spot higher. As much as he's struggling on the field this spring, there's nobody better for a clubhouse than a finesse veteran with a good sense of humor.
Atlanta's outfielders have many great years ahead of them.
Young impact players: RHP Luis Avilan, 1B Freddie Freeman, RF Jason Heyward, RHP Craig Kimbrel, LHP Mike Minor, SS Andrelton Simmons, RHP Julio Teheran, LF Justin Upton, RHP Jordan Walden.
Old impact players: RHP Tim Hudson, OF Reed Johnson.
The Atlanta Braves develop their homegrown talent quickly.
Most of the "young impact players" came from within. Freeman, Heyward and Kimbrel, specifically, experienced Major League Baseball in their early 20s and already have multiple seasons under their belts.
Hudson and Johnson can still be effective in particular matchups. Regardless of stats, their veteran presences are invaluable.
Few other MLB teams can look forward to midseason reinforcements like Brandon Beachy and Brian McCann. When healthy, they rank among the league's best at their respective positions.
The only knock against Atlanta's age profile is the lack of experience among middle relievers.
Young impact players: RF Jay Bruce, LHP Aroldis Chapman, RHP Mat Latos.
Old impact players: RHP Bronson Arroyo.
Virtually anything is possible when dozens of players meet at the appropriate stages of their careers.
The Cincinnati Reds won 97 regular-season contests last season and retained all the key contributors.
Their age profile improved when Miguel Cairo and Scott Rolen departed. Shin-Soo Choo, 30, and Jack Hannahan, 33, now occupy those roster spots.
Cincy has the perfect blend of pitchers: athletic men who get by on raw stuff and veterans to preach to them about harnessing it.