Being a Major League rookie, no matter your signing bonus, your age or your prospect pedigree, means starting at the bottom of the clubhouse totem pole. Off the field, first-year players are generally expected to keep to themselves, say the right things to the media, and earn respect from their veteran teammates by blending in as "one of the guys." But between the lines, they're encouraged to produce as loudly and emphatically as they can. 
Which is why nobody in the Yankees' or Dodgers' circles, or, for that matter, around all of baseball, took issue with how Aaron Judge and Cody Bellinger asserted themselves this season, the first full Big League campaign for each. The game has been trending younger for a generation now, with teams relying on hordes of rookies more than ever. But 2017 may truly have been the best season in baseball history to be a freshman, and Judge and Bellinger were two huge examples why. 
Both became immediate stars and essential parts of powerful lineups: Bellinger of the historically-great Dodgers and Judge of the storied Yankees. It isn't easy setting Yankees records, yet even before the All-Star break Judge had surpassed the franchise rookie home run mark, set in 1936 by the legendary Joe DiMaggio. 
"It's a pretty special name he passed," says Yankees Manager Joe Girardi. "You talk about the home runs, the walks, the average he's hit for, the defense he's played. It's very incredible what he did in the first half of the season."
Judge slammed his record-breaking home run on July 9 against the Brewers, a towering shot to center field at Yankee Stadium that travelled 432 feet, according to Statcast™. The scary part is, that wasn't even one of the 10 longest home runs he hit in 2017. 
Simply put, Judge captivated the baseball world with his never-before-seen combination of size and power. At 6 foot 7 and 282 pounds, the 25-year-old doesn't resemble an NFL linebacker; he resembles a big NFL linebacker, and he pushes the limits of how far a human being can hit a baseball. All that strength resulted in the farthest home run through the first five months of 2017, a 495-foot blast that Judge rocketed over the Yankee Stadium bleachers on June 11. He also boasted a number of the hardest hit baseballs, as measured by the Statcast™ metric exit velocity, with five homers -- headlined by a 121-mph laser on June 10 -- registering at 117 mph or more. 

Bellinger's blasts didn't light up the Statcast™ leaderboard like Judge's did but, really, expecting them to would have been unfair. After all, the 6-foot-4, 210-pound Bellinger wasn't in the Majors on Opening Day and didn't debut until an injury to Adrian Gonzalez opened a roster spot April 25. From there, though, the 22-year-old instantly became a household name -- attracting plenty of attention from fans who remember the heyday of his father, Clay, who coincidentally debuted with the Yankees -- thanks to one of the most prolific introductory months in Major League history. 
Bellinger hit seven home runs over his first 16 games, and went on to launch 25 in a truncated first half, over which time he transformed from forgotten prospect to the cleanup hitter of baseball's winningest team. He, too, shattered his franchise's single-season rookie home run mark, set in 1993 by an unheralded catcher named Mike Piazza. For good measure, Bellinger also became the first Dodgers rookie to hit for the cycle.
"Everybody knew this was going to happen," said Dodgers rookie catcher James Farmer. "When I was in [Class-A Advanced] Rancho [Cucamonga] and [Double-A] Tulsa, he was putting up stupid numbers, as well. He is a great kid and is very humble and enthusiastic."
All of which made Judge and Bellinger two sides of a similar coin in 2017. Two young, baby-faced sluggers shining like supernovas carried by their prestigious power. One on the East Coast, one on the West Coast. One righty, one lefty. Both doing it for two of baseball's most revered franchises in the sport's two largest media markets.
When all was said and done, Judge and Bellinger concurrently put together two of the best rookie seasons in baseball history -- and the most productive, power-wise, as a tandem. Just 12 rookies have ever hit more than 35 home runs in a season, and Judge and Bellinger rank as the first pair to do it in the same year. 
McGwire set the previous rookie record with 49 homers in 1987, 31 years after Frank Robinson knocked 38 in 1956. Robinson had previously shared the rookie home run record with Wally Berger, who hit 38 in 1930 for the Boston Braves. It was another three decades until Judge would break McGwire's mark, smashing his 50th blast of the season on Sept. 25 in a multi-homer game. 

McGwire, Judge, Bellinger and Robinson certainly used their power to put together some of the best rookie seasons in baseball history. But to focus only on power would be to ignore some of the best all-around rookie seasons ever. 
For possibly the best, look no further than Angels center fielder, and two-time AL MVP, Michael Trout. Before he was the best player in baseball, Trout was the next big thing, the top prospect in the sport at the time of his debut in 2011. And much like Judge did in his first Major League stint, Trout struggled. 
"This game will humble you quickly," Judge says. "I've got it in my notes, I look at it every day -- .179, what I hit last year."
But both players returned for their official rookie seasons and took the baseball world by storm. Trout's 2012 campaign is the best rookie year in baseball history by Wins Above Replacement (10.8), the catch-all metric designed to gauge a player's overall value. WAR is meant to be more of a guide than an absolute answer. That said, Trout was excellent on both sides of the ball as a rookie, hitting .326/.399/.564 with 30 home runs, a league-leading 129 runs scored and 49 stolen bases, all while playing a solid center field. 
WAR allows us to compare players across generations, which is why we can use it to examine the rookie seasons of Judge, Trout and Shoeless Joe Jackson through a similar lens. Jackson's 9.2 WAR from his rookie year in 1911 is the second-highest ever, behind Trout's aforementioned 10.8 from 2012. Baseball was immeasurably different then than it is now, but Jackson actually had more extra-base hits -- including 19 triples -- than Trout did in their respective rookie campaigns. Although it wasn't calculated at the time, Jackson would have led baseball with a .468 on-base percentage that season. He also hit .408. 
Trout was the runner-up in AL MVP voting after his first full season, in addition to grabbing the AL Rookie of the Year Award. Jackson placed fourth; DiMaggio eighth; and McGwire sixth; while Piazza ranked ninth in the NL voting. 
Only two players ever have won Rookie of the Year and MVP awards in the same season: Fred Lynn in 1975 and Ichiro Suzuki in 2001. Lynn was a sensation much like Judge and Bellinger, albeit more of a doubles hitter, during his breakout year for the Red Sox in 1975. The sweet-swinging lefty hit .331/.401/.566 with 21 home runs and 105 RBI. He led the AL in runs, doubles and slugging, and won a Gold Glove Award. 
Ichiro was 27 years old when he came over from Japan's Nippon Professional Baseball League in 2001. He brought with him a swing unlike anyone in the Major Leagues had ever seen, an entire foreign press corps that followed his every move, and a nation's worth of questions wondering if his style would work in the United States. 
It didn't just work. Ichiro was a massive success, and the Mariners were one of the all-time winningest teams in 2001, just as the Dodgers were this year, with Bellinger anchoring their lineup. But Seattle's best player hit at the top of the order. Ichiro led the AL in batting and hits that season and boasted a .350/.381/.457 slash line with a league-leading 56 stolen bases.  
Like Judge's success this season, Ichiro's monster 2001 campaign paralleled another incredible rookie season in the National League, when Jose Pujols introduced himself to the Big Leagues. Ironically, Pujols wasn't expected to crack the Cardinals' Opening Day roster because of McGwire's stranglehold on the first base position. But Pujols did it, and he quickly became one of the game's best players, setting an NL rookie record with 130 RBI and becoming the fourth rookie in MLB history to hit .300 with 30 home runs, 100 runs scored and at least 100 RBI. The other three: Hal Trosky (1934), Walt Dropo (1950) and Ted Williams (1939). 

Pujols and Ichiro (and likely Trout) are destined for Cooperstown, where they will join Williams, Robinson, Piazza and some of the other top rookies in baseball history. 
That includes Christy Mathewson, who owns the highest first-year WAR (9.1) of any modern pitcher enshrined in Cooperstown. Think about the numbers "The Big Six" put up in his rookie campaign in 1901: 20 wins, a 2.41 ERA in 40 games, 38 starts and 36 complete games.
Such stats are unfathomable now, which is one reason why so few rookie pitchers put up a similar season in terms of value until 75 years later. It was 1976 when Mark "The Bird" Fidrych debuted for the Tigers and captivated the baseball world with a season of eccentric dominance. Fidrych will always be known as the pitcher who talked to the baseball, but his numbers have endured along with his reputation: 19-9, a league-best 2.34 ERA, 24 complete games, and a 9.6 WAR. 
No rookie pitcher has completed that many games in his inaugural campaign since, and none likely will ever again. Tom Seaver posted a respectable 18 complete games in his 1967 rookie year. Fernando Valenzuela fired a league-leading 11 complete games in his transcendent 1981 campaign for the Dodgers. But even by 1984, Dwight Gooden's blazing rookie campaign for the Mets, the complete game was falling out of fashion. 
Different numbers can help us appreciate Gooden's dominance that year, like his modern-era rookie-record 276 strikeouts. As great as Gooden was that year at missing bats, he wasn't better, at least by the strikeouts per nine innings ratio, than Cubs righty Kerry Wood was as a rookie. In 1998, Wood registered an all-time high of 12.6. Active hurlers Yu Darvish (10.4 in 2012) and Jon Gray (9.9 in 2016), along with the late Jose Fernandez (9.8 in 2013), rank just behind Wood and Gooden on the all-time rookie strikeouts per nine list. 
Gray hasn't faced Judge, but Darvish faced the slugger three times with Texas before joining forces with Bellinger on the Dodgers in July. Judge's verdict? 0 for 3 with two strikeouts.
But against almost everyone else, his bat spoke volumes -- louder than any rookie who has ever played the game. 
This article appears in the World Series Program. To purchase a copy, visit mlbshop.com.