The kids change how baseball is played. That's the fun part. Every so often, a special class of young players enters Major League Baseball and they create a minor revolution. In the early-to-mid 1950s, for instance, there was an unprecedented wave of young superstars. This was in part because of the erasing of the color line, but it was also just a special time for young baseball players. Willie Mays and Mickey Mantle came into the game, so did Henry Aaron, Eddie Mathews, Ernie Banks, Frank Robinson, Al Kaline, Roberto Clemente and so on.
They changed baseball, made it more athletic, faster, a little bit more thrilling.
In the mid-to-late 1960s, another generation of fantastic young players came along, this time led by great young pitchers like Tom Seaver, Steve Carlton, Jim Palmer and Nolan Ryan, and they too would define baseball, dominating the game in the '70s, striking out a lot of batters, forcing offenses to scrounge for runs with small-ball tactics and stolen bases.
And in the late 1980s and early '90s, as everyone knows, an amazing group of young hitters came into baseball -- Barry Bonds, Ken Griffey, Frank Thomas, Jeff Bagwell, Robbie Alomar, Mike Piazza, Gary Sheffield, etc. -- and, of course, they changed baseball again.
Right now, we are in the midst of one of the great inflows of young baseball talent since the 1950s. There were so many brilliant 25-and-under players in 2016 that it was dizzying. The list begins, of course, with Mike Trout, who has been so great for so long that it boggles the mind to think he only turned 25 in August. Trout has 49 Wins Above Replacement already; by that measure, he's the most accomplished 25-year-old player in baseball history, ahead of even Ty Cobb.
But, of course, the youth movement only begins with Trout. Three of the top 5 Most Valuable Player vote-getters in both the American League and the National League were 25 and younger -- including both winners. Chicago's Kris Bryant, who just turned 25 in January, won the NL MVP Award. He led the league in runs, bashed 39 homers, and led the Cubs to their earth-shattering World Series triumph.
Boston's Mookie Betts, who turned 24 in October, led the AL in total bases. Baltimore's Manny Machado (24) had another brilliant year with 40 doubles, 37 home runs and his typical brilliant defense at third base and shortstop. Miami's Christian Yelich and Philadelphia's Odubel Herrera both had terrific and underappreciated seasons. Chicago's Javier Baez showed remarkable gifts in the postseason.
Colorado's Nolan Arenado will turn 26 in April, so he's a touch older than the others, but he led the league in homers and RBIs for the second straight season and, like Machado, he's a defensive phenomenon.
And all this doesn't even include Bryce Harper, who just turned 24 and will try rebound to 2015 form, when he led the league in runs, homers, on-base percentage and slugging percentage.
Let's talk for a minute about the young shortstops. In the mid-1990s, as you will remember, an incredible shortstop trio entered baseball -- Derek Jeter in New York, Alex Rodriguez in Seattle and Nomar Garciaparra in Boston.
Now, there are no fewer than seven potential shortstop superstars in the big leagues, and that doesn't even include numerous close-to-ready mega-prospects like the Yankees' Gleyber Torres, the Mets' Amed Rosario, Philadelphia's J.P. Crawford or Atlanta's Dansby Swanson.
Los Angeles' Corey Seager
Well, Seager is already a superstar after hitting .308 and slugging .512 in winning the NL Rookie of the Year Award. There are those who think he has the talent to overtake Trout as the best player in baseball.
Houston's Carlos Correa
Correa is still just 22, he hits with power, he has already been a fabulous player and most believe he's just scratching the surface of his talent.
Cleveland's Francisco Lindor
Lindor turned 23 in November. He might be the best fielder in baseball right now, any position. Lindor has hit .300 in his first two seasons, but he's still developing as an offensive player. He's the heart and soul of Cleveland baseball.
Chicago's Addison Russell
What in the world was Oakland thinking when it traded Russell away? He's a work in progress offensively -- he did surprise a lot of people with 21 home runs in 2016 -- but what a defender.
Boston's Xander Bogaerts
Boston has so many good young players -- and outfielder Andrew Benintendi is the consensus best prospect in baseball -- that Bogaerts gets overlooked. Hard to overlook a young shortstop with power and speed; he has won the AL Silver Slugger Award for best-hitting shortstop each of the past two seasons.
Washington's Trea Turner
Turner has only played 100 big leagues games, but he did hit .342 and slug .567 in a half season last year with Washington. He also stole 33 bases. Turner's future looks just about unlimited.
Colorado's Trevor Story
OK, so you remember that Story hit six home runs in his first four games in the big leagues. His season was shortened by injury, but he hit 27 homers in 97 games and played good defense. Story also looks like a star in the making.
That's just incredible to have seven young shortstops on the brink of stardom. Maybe it's because these kids grew up watching A-Rod and Jeter and saw the possibilities. And, I think, like the wave of young players in the past, this new group will define how baseball will be played for the next decade or so. How? Well, I think they are taking baseball away from the one-dimensional player. Years ago, Bill James came up with what he called the defensive spectrum -- it is a concept that arranges all the positions on the field from easiest to hardest.
The defensive spectrum looks like so:
DH - 1B - LF - RF - 3B - CF - 2B - SS - C.
Designated hitter is obviously the easiest defensive position, catcher and shortstop are obviously the hardest. In baseball, historically, most of your great hitters were on the left side of the spectrum. That seems logical. If you have a great hitter, chances are he's not a great fielder -- so you would put him at one of the easier positions. Ted Williams. Harmon Killebrew. Willie McCovey. Jim Thome. Frank Thomas. On and on.
And it was believed that the defensive demands for playing second base or shortstop were so overwhelming that only the rarest of players -- an Ernie Banks or Joe Morgan or Cal Ripken -- could handle those and still be an exceptional hitter.
Now, though, you look at baseball, shortstops and second basemen hit better than left fielders and about as well as designated hitters. Look for that trend to continue. The game's young stars are playing a two-way game; they don't feel limited by their position.
Put it this way: From 1950 to 2015, the average number of shortstops to hit 20-plus homers was two.
In 2016, 12 shortstops hit 20-plus homers, by far the highest total in baseball history. And you can look for that number to grow. These kids just don't know that shortstops aren't supposed to hit and hit with power.
MLB.com columnist Joe Posnanski is a No. 1 New York Times best-selling author, an Emmy Award-winning writer and has been awarded National Sportswriter of the Year. This story was not subject to the approval of Major League Baseball or its clubs.