It's a wonderful thing to be young and supremely talented, but only one of those attributes can last for more than a few years. By age 25, there is generally a fair indication of just how talented a young Major League player is, and how high his career might soar.
Clayton Kershaw, for one example on the extreme, collected two National League Cy Young Awards in three years, three consecutive league ERA titles and a contract extension for the record books -- an impressive haul for someone just 25 years old, to be sure.
Kershaw turns 26 on March 19, and he'll leave behind an impressive array of talent still 25 years old or younger, an unofficial but well-worn age group for evaluating baseball accomplishments over the years.
Award winners, All-Stars, amazing athletes -- all with no more than 25 years on the planet.
The conversation about baseball players in the 25-and-under category heading into 2014 begins and ends with Kershaw's neighbor to the south: Mike Trout, the Angels' stupendous outfielder.
But Trout is not alone in being young and successful in his early 20s. There's a treasure trove of talent in that age demographic: the strong swings of Miami's Giancarlo Stanton and Tampa Bay's Wil Myers, a host of rising stars in Atlanta led by Freddie Freeman and the mound mastery of 2013 phenom Jose Fernandez of the Marlins. There's two-time World Series champion Madison Bumgarner of the Giants, and the overall excellence of players like the Nationals' Bryce Harper, the Orioles' Manny Machado and the Dodgers' Yasiel Puig.
And that's just a partial list. But that list, with Kershaw growing out of the age group, is headed by Trout, without a doubt.
Through his age-21 year, the Angels phenom established one of the most impressive starts to a career. He didn't turn 22 until last August, so by generally accepted standards, this will be considered his age-22 season in 2014, and he has a stellar resume built already.
Among Trout's accomplishments in his first two seasons in the bigs, there are some that are age-specific and -- perhaps more notable -- historic for players of any age. He is the first player in Major League history with at least 50 homers and 70 steals before turning 22, and he is just one of four players to bat .320 with 50 homers and 200 runs scored in his first two full seasons, joining Joe DiMaggio, Ted Williams and Albert Pujols. Trout also joins Willie Mays (1957-58) as the only players to bat .320, hit 25 or more homers and steal 30 or more bases in two seasons at any point of a Major League career.
Trout provides no reason to expect that his combination of speed, power and agility will take a step backward this year. He is clearly in his element.
"I just like competing," Trout said. "I like being on the field. I like the adrenaline rush, running on the field, making that big play, getting that big hit. That's what I love to do, is play the game."
Trout is truly one of a kind, but there are teams currently holding a pair or an even better hand when it comes to being served by youth.
Atlanta has become a hotbed for young talent. The Braves have invested millions this winter in lucrative multiyear deals with first baseman Freeman (24), outfielder Jason Heyward (24), shortstop Andrelton Simmons (24) and right-hander Julio Teheran (23), along with 26-year-old closer Craig Kimbrel.
"We were able to tie up key components of our club for a long time," Braves general manager Frank Wren said.
In Miami, Stanton (24 in '14) became among the fastest and youngest in Major League history to hit his 100th homer last June, and Fernandez (21) had one of the best seasons for a pitcher under 21 en route to NL Rookie of the Year Award honors.
Position talents like Harper (21) and Machado (21) and pitchers such as Stephen Strasburg (25) and Bumgarner (24) burst onto the scene in the last several years, part of a wave of stellar young players that continues into 2014. Last season saw the debuts of more intriguing youngsters, from the American League Rookie of the Year Award-winning Myers (23) and NL ROY Award runner-up Puig (23) to Pirates pitcher Gerrit Cole (23), Rangers second baseman Jurickson Profar (21), Red Sox shortstop Xander Bogaerts (21) and Mariners pitcher Taijuan Walker (21). And how about Michael Wacha (22) and Trevor Rosenthal (24), part of the Cardinals' kiddie corps of a pitching staff that had so much October success?
Heading into 2014, there are also a good number of young players who have been around a bit, such as the Rangers' Elvis Andrus (25), the Cubs' Starlin Castro (24), the Royals' Eric Hosmer (24) and White Sox's Chris Sale (25).
But even among those a few years older, Trout is already the dean of a very impressive younger set in the Majors, having posted two of the best seasons from a player at any age, much less by one in his early 20s.
"I really can't explain just the last couple years of my life," Trout said upon arriving at Spring Training. "It's been great. Having fun doing it. That's what I wanted to be as a kid growing up, and I'm taking full advantage of it. No better place to be right now."
John Schlegel is a national reporter for MLB.com. You can follow him on Twitter at @JohnSchlegelMLB.