What was arguably the best rookie class in history last season included several youngsters who played enough in 2015 to make an impression while still retaining their rookie status heading into '16. Call them the "re-rookies," and this year's bunch has plenty of talent.
Whether any will be in the mix for the Rookie of the Year Awards remains to be seen. Actually, many of them might not even start the season in the bigs. But they'll all get a second crack as official rookies under Major League rules.
A few of the top names whose rookie status extends into 2016:
Corey Seager, Dodgers
He was a September callup, but it sure seemed like Seager had more of an impact on his team's season than that. Considering he played a key starting role down the stretch for a division-winning club, he and the Dodgers got about as much out of his debut month as could be expected.
Seager, who could be MLB Pipeline's No. 1 prospect when its new rankings are revealed on Friday at 9 p.m. ET on MLB Network, had four homers among his 28 hits -- registering a slash line of .337/.425/.561 and reaching base safely in 24 of his 25 starts. It was all there on display quickly for Seager, and now he takes over for Jimmy Rollins at shortstop, having already gotten his career off to a strong start heading into his full rookie campaign.
Byron Buxton, Twins
Buxton was last year's top prospect and will be in the mix for that crown again. He also defines the parameters of rookie status. Buxton went right up to the limit for at-bats with 129, falling one shy of the threshold of 130. While he accrued 113 days of Major League service time -- well beyond the limit of 45 days -- most of that time was spent on the disabled list or after rosters expanded on Sept. 1, so per rookie rules, he retains his status on that front, as well.
Buxton, 22, could use a second chance to make a shining first impression in the bigs. He sustained a thumb injury just 10 days after his debut, went on the DL and didn't return to the big club until late August, winding up with a .209/.250/.326 line that might signal the need for a little more seasoning in the Minors.
Steven Matz, Mets
Like Seager, Matz made the most of his callup and took his contributions into October. He had a 2.27 ERA over six starts, becoming the first Mets pitcher ever to allow two runs or fewer in his first five assignments, and he added three strong postseason starts during the Mets' run to the World Series. The lefty is slated as the fourth starter behind right-handers Matt Harvey, Jacob deGrom and Noah Syndergaard, and that's not a bad place for a re-rookie to be at all.
Trayce Thompson, Dodgers
A switch in uniforms makes this a different kind of second rookie season for Thompson, brother of shooting star Klay of the NBA's Warriors. Thompson was another player who pushed the rookie limits, with 122 at-bats for the White Sox -- posting a .295/.363/.533 slash line while playing all three outfield positions. He and fellow re-rookie Micah Johnson made the switch to Dodger Blue in December, and Thompson finds himself part of a crowded Dodgers outfield. Where he fits is still a bit of a mystery.
Mikie Mahtook, Rays
Talk about powerful first impressions. Nine homers in 105 at-bats, most of it in a huge September/October, and yet Mahtook might still start 2016 at Triple-A Durham in another case of a crowded depth chart. Perhaps it's a cautionary tale about small sample sizes, too. After six shuttle trips lasting a total of 24 days, Mahtook batted .353 after his Sept. 1 callup, including a five-hit game and six of those nine homers. With four homers all year for Durham before he went off for Tampa Bay, the Major League sample size might not foretell such a power-packed future. Still, Mahtook did everything he could to impress, and yet there's no guarantee for Opening Day.
Fact is, not all re-rookie seasons are right on the horizon. Joey Gallo, arguably the Rangers' top prospect, showed a glimpse of his raw power but amassed 57 strikeouts in 108 at-bats, so he's due for another stint in the Minors. That's the probable fate for September callups such as Nationals shortstop Trea Turner (.225, 40 AB) and Giants outfielder Jarrett Parker (6 HRs, 1.163 OPS, 49 AB), too.
But a strong September debut has Brewers starter Zach Davies in a good place, riding a 15-inning scoreless streak to end 2015 and heading into Spring Training penciled in as Milwaukee's fourth starter.
Where they'll all end up might still be the stuff of conjecture, but the re-rookies of 2016 will be out there this spring with some Major League experience under their belts, hoping to use it to their advantage as soon as possible.
John Schlegel is a national reporter for MLB.com. You can follow him on Twitter @JohnSchlegelMLB. This story was not subject to the approval of Major League Baseball or its clubs.