Why do free agents continue to turn down Nationals?
2:20 | MLB
Why do free agents continue to turn down Nationals?
Friday February 5th, 2016

Friday marks Hank Aaron’s 82nd birthday, and while Aaron’s 755 career home runs are no longer the most in major league history, that figure still looms large over the game. Only one man, of course, has ever topped that figure, and Barry Bonds's accomplishment of hitting 762 home runs is so tainted by his reported use of performance-enhancing drugs that many baseball fans still consider Aaron to be the game's true home run king. 

Will anyone reach Aaron's total again? There are several active superstars who are compiling remarkable numbers at young ages as well as a few accomplished veterans who continue to move up baseball’s career home runs list. Yet, according to noted statistician Bill James, only one current player has any chance of matching 755, and his odds are less than 1%.

The formula, known as the Favorite Toy, was devised by James in 1981 to, in his words, “estimate accurately a player's chances of attaining some particular career goal.” The details can be found here, but essentially, the Favorite Toy factors in the player’s distance from the goal, his momentum or pace in that particular category and how much time he has left to reach that goal based on his age. It then spits out a percentage representing the player’s chance of achieving that goal. With that in mind, here’s a look at the six players who would seem to have the best chance and exactly what they would have to do to match Aaron’s career home run total.

Players are listed in order of their career home run totals; listed ages are their 2016 playing ages.

Alex Rodriguez, Yankees
Age: 40

Career Home Runs: 687
Needs: 68

Rodriguez is fourth on the career home run list behind Bonds, Aaron and Babe Ruth (714), but he'll turn 41 in July and has just two years remaining on his contract with the Yankees. What's more, there's no guarantee Rodriguez will play beyond that contract, given that he is now a full-time designated hitter who has a history of repeated performance-enhancing drug violations and will be 42 when he reaches free agency after the 2017 season. In order to catch Aaron before then, Rodriguez will have to average 34 home runs per year over the next two seasons.

That figure may not sound impossible given that Rodriguez hit 33 last year at the age of 39, but he hasn’t hit 34 or more home runs in a season since 2008, and he hit a total of just 71 home runs in the four years before his '14 suspension. That said, Rodriguez needs just 27 more home runs to match Ruth’s total, which now seems well within his reach.

Albert Pujols, Angels
Age: 36

Career Home Runs: 560
Needs: 195

Pujols is 14th on the career home run list, needs just 24 homers to move past Mark McGwire into the top 10 and is under contract with the Angels for six more years. But he’d have to average 32.5 home runs per year over in that time to get to 755. Pujols did hit 40 home runs last year, but before that, he had not hit more than 30 since 2011. What’s more, Pujols will open the 2016 season on the disabled list after having surgery to repair the plantar plate in his right foot. Simply staying on the field through the end of his contract will be a challenge for Pujols; catching Aaron is likely an impossibility.

Miguel Cabrera, Tigers
Age: 33
Career Home Runs: 408
Needs: 347

The 2016 season will be the first that Cabrera will play under the eight-year, $248 million extension he signed with Detroit last March, one that will take him through his age-40 season. He would have to average a whopping 43.375 home runs per year over the course of that contract, however, to catch Aaron. By way of comparison, Cabrera hit just 43 home runs in the last two seasons combined. Pujols had 67 more home runs than Cabrera at the same stage of his career and has virtually no chance of catching Aaron. Cabrera’s body has started to break down earlier than Pujols’s, and he’s further away from 755. He will not get there.

Wilfredo Lee/AP

Giancarlo Stanton, Marlins
Age: 26

Career Home Runs: 181
Needs 574

Stanton will be 38 after his record-setting 13-year, $325 million contract expires in 2027 and 39 after the option year in '28, so he’s likely to play beyond his current contract (which also contains an opt-out after the 2020 season). To match Aaron’s career home run total, however, he’ll have to hit more home runs over the remainder of his career than Harmon Killebrew, who is 11th on the career home run list, hit in all 22 of his major league seasons. Even if Stanton plays until the age of 40, he’d have to average 38.27 home runs per year over the next 15 years to catch Aaron. His current career high is 37, and he has averaged just 114 games played per year over the last four seasons at an age when he should be his healthiest.

Mike Trout, Angels
Age: 24

Career Home Runs: 139
Needs 616

Tout is the one active player with a better-than-zero chance of catching Aaron, per the Favorite Toy formula, with a 0.76623% chance of getting to 755. He also needs to out-homer Jim Thome’s entire 22-year career to match the Hammer.

Best In Class: Which teams have the best—and worst—prospect rankings

If Trout played through the age of 40, he’d have 17 seasons remaining in his career and would have to average 36.24 home runs per year over that span to catch Aaron. So far, Trout has hit more than 36 home runs in a season just once, but that came last year, when he hit 41 at the age of 23. Trout has seen his isolated slugging increase significantly in each of the last two seasons, however (from .234 in 2013 to .274 in '14 to .290 last year), and he could potentially continue to add power as he moves toward a hitter’s typical late-20s peak. That makes that 36.24 home run average much more feasible for the 24-year-old Trout than a 34-homer average is for a 40-year-old Rodriguez or a 32.5-homer average is for a 36-year-old Pujols.

What’s more, every season in which Trout surpasses 36 home runs is going to bring that average down. For example, if he hits 41 home runs again in 2016, he’ll “only” have to average 35.9 homers for the next 16 years to catch Aaron. None of that means that Trout is even slightly likely to catch Aaron, but unlike the four men previously discussed, he actually has a chance.

Bryce Harper, Nationals
Age: 23

Career Home Runs: 97
Needs: 658

To put that 658 in context: That’s two shy of Willie Mays’s career total of 660. As great as Harper is expected to be—and as great as he actually was last year when he led the National League with 42 home runs and became the youngest player to win his league’s MVP unanimously—we still have no idea what shape his career is going to take. Can he repeat his 2015 season? Can he improve on it? Will he foul up his swing trying? Will he get hurt again, like he did in 2013 and ’14?

Harper is a year younger than Trout, giving him 18 seasons to go if he plays through his age-40 season. Thus, he’d have to average 36.6 home runs per year over that span to catch Aaron. That’s only a smidge more than what Trout would have to do, but Harper lacks Trout’s projectable trajectory at this point. A year from now, a similar analysis may find that Harper has a better chance of catching Aaron than Trout (with 43 home runs in 2016, Harper would have more career home runs than Trout after their respective age-23 seasons). But for now, believe it or not, Harper is still establishing himself.

Certainly the prospect of watching Harper and Trout climb the career leader lists in not just home runs but also a host of other categories is thrilling to think about. But as great and as young as they both are, projecting either of them to reach Aaron’s career home run total is pure fantasy.

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.