A version of this story first appeared on MLB.com on Jan. 4.
Bryce Harper landed on the cover of Sports Illustrated when he was 16 years old. He was a No. 1 overall Draft pick at age 17, a National League Rookie of the Year at 19 and a unanimous MVP at 23. The number of players who share Harper's prodigious career path is extremely small.
What kind of player will Harper be for the Phillies, who agreed with the outfielder on a record-breaking contract? Using a similar method as he did to answer the same question for Manny Machado, MLB.com's senior data architect Tom Tango crunched the numbers to find historic comparables for Harper through his age-25 season. The list is derived from a similar mix of Harper's wins above replacement progression (in this case, 4-plus WAR in the player's age-25 season, 7-plus in his most recent two seasons, 9-plus WAR over his most recent three and 10-plus over his most recent four) and a weighted WAR between 3.8 and 4.3 range that mimics Harper's 2018 performance. Unlike Machado, Tango looked just at offensive WAR since Harper's defensive metrics have been so volatile in recent seasons.
That blend yielded 15 former position players that run the full gamut from Hall of Famers to players whose stars burnt out too soon:
Craig Biggio, Ellis Burks, Carl Crawford, Toby Harrah, Bob Horner, Gregg Jefferies, Barry Larkin, Bill Melton, Tim McCarver, Ken McMullen, Raul Mondesi, Ivan Rodriguez, Scott Rolen, Matt Williams, Dave Winfield.
Again, it's impossible to forecast just where Harper's next five to 10 years will take him. But here are some best- and worst-case scenarios for the superstar culled from this list of his historical peers.
There are some parallels here. Winfield garnered an immense amount of attention when he was drafted by five different teams in three different sports, and needed even less seasoning than Harper as he bypassed the Minors and broke into "The Show" at 21. Like Harper, Winfield dealt with tons of expectations, particularly during his eventful tenure with the Yankees.
But don't forget how gifted Winfield was as a hitter. From the time he turned Harper's age of 26 through his age-35 season, Winfield submitted just two seasons with a league-adjusted OPS+ below 120, ultimately hitting .290/.359/.496 with 256 home runs in that decade-long span. Winfield might not have been, say, Mickey Mantle -- a player often linked with Harper over the beginning of his career -- but he was a first-ballot Hall of Famer and one of the best hitters of the 1980s. That's an excellent fate for any player, including Harper.
Few players in history share Biggio's career trajectory as he transitioned from a catcher to second baseman to outfielder, though both he and Harper grew up as backstops. What Harper can strive for is Biggio's consistency: The Hall of Famer compiled 26.6 offensive WAR and a 129 OPS+ from his age 26-30 seasons, per Baseball-Reference, and 25.6 oWAR and a 122 OPS+ from ages 31-35. Biggio's pair of top-five finishes in NL MVP voting came in his age-31 and -32 seasons, and he remained largely league-average as a hitter into his late 30s.
Harper's game is different from Biggio's, as he's more of a swing-for-the-fences type with a larger frame. But Philly would likely be content if Harper remained a top-25 talent in the back half of a long-term contract.
Larkin, as it turns out, is a guidepost for both Harper and Machado's careers moving forward. We highlighted how Larkin only got better with age, capturing his lone MVP at 31 and maintaining an All-Star level until he was 36. While Harper's game as a corner outfielder is centered more on power than Larkin's blend of high average, speed and defense, the Phillies would probably be thrilled if he followed Larkin's example and put up somewhere between 3 and 7 WAR over each year of the next decade.
Horner burst into the Majors with force just like Harper, knocking 23 homers in 89 games with the 1978 Braves to take home the NL Rookie of the Year. In fact, the first six seasons of each player's career don't look all that different:
Horner, 1978-83: 657 G, .282/.341/.521, 158 HR, 457 RBI, 132 OPS+
Harper, 2012-17: 768 G, .285/.386/.515, 150 HR, 421 RBI, 140 OPS+
Horner was on track for a stellar career until he hit a run of bad luck that Harper hopes to avoid. He fractured his right wrist and missed most of his age-26 season, and then compiled two more above-average seasons before collusion among MLB owners deprived him of a free-agent offer and forced him out of the big leagues. Horner came back to the Majors in 1988, but logged just 60 games before a shoulder injury sidelined him. He retired the following spring at age 31.
Harper won't face the same off-the-field threats as Horner, but the third baseman's injury history -- an issue Harper has dealt with himself -- also kept him from putting up bigger numbers.
Melton peaked at 25 when he led the AL with 33 home runs with the White Sox, but his career spiraled the following year when he suffered two herniated disks while trying to break his son's fall from a garage roof. The disks cut into Metlon's sciatic nerve, sapping him of his power, and the third baseman was out of the Majors by age 31.
While Harper hasn't suffered an injury of that magnitude, he has had his own struggles with lingering shoulder pain in 2016 and a significant bone bruise in his left knee the following season.
Jefferies, like Harper, entered the Majors on a wave of hype as the first two-time winner of Baseball America's Player of the Year Award. It looked as if Jefferies would deliver on much of that promise by the time he was Harper's age, putting up batting averages of .342 and .325 in his age-25 and -26 seasons. But Jefferies' performance took a nosedive in his first season with the Tigers in 1999, and his career was effectively over the following year when he tore his right hamstring at age 32.
Jefferies' 103 OPS+ from ages 26 through 30 was respectable enough, but that figure would not be palatable with Harper's record-breaking deal. Should Harper exit baseball before his 33rd birthday like the three players listed above, his contract could go down as one of the most unfortunate in history. Certainly, he will be motivated to make sure that doesn't happen.