But a second season could reaffirm greatness, too, the way Dustin Pedroia's did with an American League MVP Award performance following his award-winning debut, or the way Albert Pujols' did with the second of 10 consecutive 30-homer, 100-RBI seasons to begin his career.
Really, the best-case scenario is it could be more of the same, the way the Braves' Craig Kimbrel played as a sophomore in 2012. He displayed every bit of the dominance as a closer in his second year as he did in his first, actually lowering his ERA to 1.01 and raising his strikeouts per nine innings to 16.7 -- an all-time Major League record.
As Kimbrel heads into the meat of his career, he has back-to-back seasons that show a ton of promise for the future of the ninth inning in Braves games.
"I look for him to do the same thing he's done the last couple years," Braves manager Fredi Gonzalez said this winter of his 2013 expectations for Kimbrel. "You don't have a crystal ball in front of you, but here he is. If he can do this for a 10-, 12-year career span, he'll be up there with some of the big names and closers, you know, the [Mariano] Riveras and [Trevor] Hoffmans and those type of guys.
"Maybe a little longer than 12 years, but I don't look for him to do anything more really. He keeps getting better because he wants to get better."
Jeremy Hellickson, Kimbrel's top rookie counterpart in the AL in 2011, made it through his sophomore season with a tiny downtick in numbers, but the addition of his first Gold Glove Award.
Rays manager Joe Maddon believes Hellickson could evolve into a consistent 200-inning contributor, which would come in especially handy now that James Shields and Wade Davis have headed off to Kansas City.
"Helli can [pitch] 200, 200-plus [innings]. Everything's got to break," Maddon said prior to the blockbuster deal with the Royals. "We've got to watch him well. He has to work for it, too. It has to be something he really wants to do. I think, if he truly wants to be that guy, it's definitely within his ability, no question."
Among other top vote-getters in the 2011 Rookie of the Year Award races, the Braves' Freddie Freeman and the Angels' Mark Trumbo didn't skip a beat. Eric Hosmer of Kansas City and Vance Worley of Philadelphia hovered a bit, while Ivan Nova and Michael Pineda had different versions of disappointing second seasons -- Nova with middling results and Pineda spending his first season with the Yankees [and maybe more] sidelined with a shoulder injury.
As usual, there is the good, the bad and everything in between when it comes to second-year follow-ups to stellar rookie seasons.
So, what do the top rookies of 2012 have to look forward to in '13? While Bill James might be able to render predictions, it's something that really is unknowable with variables abound. Will life in the Majors become that much more comfortable or take a different turn for international sensations Yeonis Cespedes of the A's and Yu Darvish of the Rangers? Will the D-backs' Wade Miley continue to consistently succeed on the mound after finishing a close second to Harper in the NL vote? Will Todd Frazier excel even more with a set position at third base with the Reds?
At the head of the class, otherworldly talent and blatant baseball savvy should mean more of the same, one would think. Particularly for Trout, it's a tough act to follow -- he posted a uniquely dominant season for any Major Leaguer, not just a rookie. And Harper put together his Rookie of the Year season at 19, a year younger than Trout, even.
Heading toward his second season, Harper isn't holding back on his expectations.
"My biggest thing is, I want to win a World Series," Harper said. "I want to put that ring on my finger and give that to the town and city of D.C. They deserve that. I think the organization deserves it. That is what my biggest goal is."
would be the best way to follow up a strong rookie season.