One of baseball's great paradoxes can be found in its salary structure. Often, just as a player is eligible to make big money, he begins to lose the ability that makes him worth all those dollars.
Players aren't eligible for free agency until they've amassed six full seasons of Major League service time. Thus, most players who hit the free-agent market are 30 or older -- just about the time when their skills start to decline.
Yankees first baseman Mark Teixeira was particularly candid about the mismatch between dollars and skills in an offseason interview with The Wall Street Journal. He acknowledged that at this point in his career (he will turn 33 next month), it's unlikely he'll generate the kind of performance that would justify his $22.5 million salary. Teixeira's performance has declined since he was in his late 20s, and it's not surprising.
In fact, it's typical. For some it starts happening at 29, for some at 33, but it happens. Players typically peak in their late 20s and start declining in their early 30s. Give or take.
"The answer is probably [that players peak] somewhere between 28 and 30," said Cardinals general manager John Mozeliak. "Does it move for each individual? Yeah, probably. So there's no one right answer."
It's essential, as any front-office person worth his or her salt will remind you, to separate the individual from the model, which is what Mozeliak was getting at. Big-picture numbers definitely provide valuable context. But every player has his own aging curve. Some guys are old at 30. Some play like youngsters at 35.
"It's body type, how they age, [things like that]," said Nationals GM Mike Rizzo. "Players all age in different rates. The more athletic the player is, I think the better that they age. Body type and diet and work ethic and all that stuff comes into it. I think it's very individual. It's a case-by-case basis, and I think if you make any blanket type of analysis, I think you're doing yourself a disservice."
One factor for players entering their peaks is experience. A 27-year-old with four or five years in the big leagues might well be better poised to take advantage of his physical prime than a 28-year-old with only a couple of years behind him. Young veterans are always a prized commodity because they have the knowledge that comes from experience, and the physical tools that come from being on the right side of 30.
As the new season approaches, we take a look at some hitters who might well be entering and exiting those crucial peak years.
Adam Jones, Orioles: Baltimore's center fielder turned 27 in August. His most comparable players through his age-26 season, according to BaseballReference.com, are Reggie Smith, who had a huge peak in his age 27-30 seasons, and Dave Winfield, who had his best season at 27. Jones is a coveted young veteran, with tons of experience for his age. He hit more line drives last year than ever before, and he matched his career high in homers and hit a career high in doubles as well.
Carlos Santana, Indians: What was widely regarded as a disappointing year for Santana was better than one may think. At 26, he increased his batting average and on-base percentage and reduced his strikeout rate while maintaining his walk rate. Now he enters his third full big league season, turning 27 in the season's first month. Santana always hit in the Minors, and that's usually a pretty good indicator that one will hit in the Majors.
Neil Walker, Pirates: Walker enters his fourth full season at 27 and is coming off a three-season stretch of hitting for decent average and moderate power. Michael Young had a similar profile at that point in his career (most similar, according to BaseballReference.com), and enjoyed a big spike at 27. Walker increased his line-drive percentage last year, and while his strikeout rate has bounced around, his walk rate has increased in each of the past two seasons. A converted catcher, Walker has become a more adept defender at second base. As he becomes more comfortable there, he might be better able to concentrate on the offensive side of things.
Brandon Phillips, Reds: Cincinnati's durable second baseman turns 32 in June. And while his production has been mostly stable, he's shown a couple of signs of aging. After hitting at least five triples every year from 2007-10, he had a total of three in 2011-12. His stolen bases have likewise fallen since his late 20s, and those are both indicators of diminishing speed. Phillips won't necessarily fall off a cliff in '13, but it's likely that the next three or four years will be worse than the past three or four.
Albert Pujols, Angels: It's unwise to bet against Hall of Fame talent, but Pujols is surely heading in the wrong direction, and he turned 33 in January. He did slug 50 doubles last year, but his 52 walks were a career low and his 76 strikeouts were tied for his second most in a season. Pujols' last two years represent a step down from the absurd peak he managed through his age-30 season, and it's difficult to envision him getting back to those heights in his mid-30s.
Nick Swisher, Indians: Swisher has been one of the most consistent players in baseball, with an OPS+ between 120 and 129 in each of the past four seasons. But he turned 32 in November, and his power the past two years was down from the previous two years. As with Phillips, there's little chance the bottom falls out for Swisher, who has a broad set of offensive skills. But for a player whose game is power and walks, any decline in either of those areas might portend bad news in the long run.
Matthew Leach is a writer for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.