ATLANTA -- Those hoping to watch Ronald Acuña Jr. extend last season's incredible post-All-Star break production should remember that his pace would have equated to 45 homers and 33 stolen bases over 162 games.
Nine different players have accounted for the 11 total 40/30 seasons in MLB history. Acuna's power and speed tools make him a possible -- and maybe in some eyes probable -- candidate to join Barry Bonds, Hank Aaron and the other members of this exclusive club. But before setting any immediate expectations for the upcoming season, it may be best to simply savor the chance to watch Acuna's progression toward potential greatness.
:: Spring Training coverage presented by Camping World ::
Acuna's MLB experience essentially consists of four months, 2 1/2 of which were stellar. Still, despite enduring a first half marred by a delayed debut and a left-knee injury, Acuna became the first player in MLB history to hit at least 25 homers with fewer than 500 at-bats at age 20 or younger.
"I don't know what that guy's ceiling is," Braves first baseman Freddie Freeman said. "He is special. He's going to be fun to watch. Just think if he didn't get hurt that month what his numbers might have been. It's going to be fun to watch him play every single day. I don't think you can really put a cap on his numbers if he stays healthy."
Acuna became the seventh player in MLB history to hit .290 with 25-plus homers and a .900-plus OPS during his age-20 season. The other members of this club are Mel Ott (1929), Ted Williams (1939), Frank Robinson (1956), Al Kaline (1955) Alex Rodriguez (1996) and Mike Trout (2012).
Trout (+11) and Williams (+1) were the only members of this group to improve their OPS+ from their age-20 season to their age-21 season. Trout is the only member who improved his OPS (.963 in 2012 and .988 in '13) during the season that followed. But for the most part, the production of the players in this group remained rather consistent.
If Acuna were just to match last season's stats -- .292 batting average, 26 homers, .917 OPS -- he'd become the 11th player (or maybe one of 12, depending on Nationals outfielder Juan Soto's success) in history to hit. 290 with 25-plus homers and a .900-plus OPS in an age-21 season. But while a similar season would certainly be acceptable, it's hard to use last year's sample size to project what Acuna might do.

Acuna hit .249 with seven homers and a .742 OPS in 43 games before the All-Star break. His MLB debut was delayed until April 25 and he missed a month when he sprained his left anterior cruciate ligament on May 27. What had the makings to be a so-so season became a National League Rookie of the Year Award campaign after he hit .322 with 19 homers and a 1.028 OPS over the 68 games played after the break.
Acuna's incredible second-half tear was aided by the mechanical adjustments that focused on getting his hands away from his body. His power surge enabled him to join Orlando Cepeda, Eddie Mathews, Tony Conigliaro, Ott, Trout, Williams, Robinson, Rodriguez and Kaline as the only players to hit 25-plus homers during an age-20 season or younger.
The top four at-bats per home run ratios produced during these specific seasons belong to Ott (13.0), Robinson (15.1), Conigliaro (16.3), Acuna (16.7) and Rodriguez (16.7).

Based on last season's at-bats total (433), Acuna would have tallied 18 home runs with his mediocre first-half pace (24.1 AB/HR) and 31 homers with his second-half pace (13.9 AB/HR). Either result would have created reason to be excited about what he is capable of doing, this year and beyond.
"When you start at the bottom and you reach this point, there's no real reason to change," Acuna said. "Nothing about the process would make me feel I need to change anything about myself or the way I do things. I think with all the team's success, you just have to remind yourself to stay humble throughout the entire experience."