It wasn't just that he was most writers' consensus pick for NL rookie of the year, or that Ben McGrath wrote in the New Yorker that "it was looking as if Heyward might already be their best position player" after a monster March in spring training.
It was also because Jason Heyward was already drawing what seemed to be an impossible comparison to another 20-year-old African-American phenom who also made his debut in the Braves outfield.
A guy by the name of Henry Aaron.
Such a comparison might have seemed the sole domain of today's hype-driven media, but it was actually Heyward's manager, Bobby Cox, who said this in spring training (via McGrath):
"There are just some guys that hit the thing, and it's, like, Oooh, that's different. That's way different. [...] I first heard that sound with Henry Aaron."
That one player would be compared to the greatest player in his franchise's history before ever playing a big league inning seems ridiculous. No one in Chicago said Starlin Castro(notes) was going to be the next Ernie Banks, and for all the hype Stephen Strasburg(notes) received, the only high-profile figure who suggested a parallel to Walter Johnson was Bob Costas.
But for some reason, Heyward kept drawing comparisons to not only the greatest Brave ever, but one of the best baseball players in the history of the game.
Hank Aaron, rookie, age 20:
122 G, 509 PA, 468 AB, 58 R, 13 HR, 69 RBIs, 28 BB, 39 K,
.280/.322/.447, 104 OPS+
Jason Heyward, rookie, age 20:
118 G, 516 PA, 435 AB, 75 R, 16 HR, 65 RBIs, 71 BB, 112 K,
.283/.391/.474, 133 OPS+
Neither carried an entire workload as Aaron's year was ended prematurely by a broken ankle and Heyward missed a couple weeks on the DL in the middle of the season.
Also, for what it's worth, Aaron was 20 his entire rookie season (he was born in February) while Heyward turned 21 on Aug. 9 of his rookie season.
Still, Heyward will almost certainly wind up with more games played, and he already has more plate appearances. Strikeouts aside, he also has better stats than Aaron in virtually every offensive category.
And it's not as if Aaron had just an average debut year, either. Though it was one of his worst seasons — Aaron would establish himself as one of the NL's top hitters in his sophomore year— his 1954 debut was one of the best rookie campaigns by any 20-year-old in history. Indeed, there have been only 12 players in baseball history who debuted that young and recorded an OPS of at least .750 in 400 or more plate appearances. Aaron's .769 OPS is 10th on that list while Jason Heyward is fourth. (Starlin Castro's .798 this season is seventh, just behind Willie Mays.)
Rookie status aside, Heyward is putting together one of the best seasons by any 20-year-old, period. If we expand that last list to include non-rookies, there have been only 35 players in baseball history who recorded an OPS of at least .750 in at least 400 plate appearances at the age of 20 or younger. Aaron is 29th of the 35 while Heyward is 11th. Of the 10 players ahead of him, seven are in the Hall of Fame. Of the other three, Alex Rodriguez(notes) will be in, Vada Pinson should be in, and Tony Conigliaro was on a Cooperstown path when his career was cut short by injury.
Not to put any additional pressure on Jason Heyward, but all those people predicting a Hall of Fame-style start to his career were right on the money. His rookie season has proven that all of those Aaron comparisons weren't as silly as they first sounded.
- Henry Aaron