Josh Donaldson is once again in the news. The 2015 American League MVP Award winner has reportedly agreed to a two-year, $29 million deal with the Blue Jays, which will effectively buy out his first two years of arbitration. This is a very lucrative deal for someone reaching arbitration for the first time, but Donaldson isn't just any other player. He's been a top-10 finisher in the AL MVP Award voting three years running, and his unusual career arc makes him arguably the most impressive late-bloomer in baseball history.
There are 24 position players since 1901 who accumulated a WAR of at least 23.0 for their age-27 through age-29 seasons. Of the two dozen, 19 are in the Hall of Fame, with the only exceptions being Barry Bonds and a quartet of active players: Albert Pujols, Alex Rodriguez, Chase Utley and Donaldson. This collection of ballplayers -- led by Babe Ruth -- finds Donaldson occupying the 19th slot, in between arguably the game's greatest second baseman, Joe Morgan, and two of its absolute top-of-the-line center fielders, Tris Speaker and Mickey Mantle. For this age, Donaldson rubs shoulders with players like Lou Gehrig and Hank Aaron, Duke Snider and Willie Mays, Ty Cobb and Mel Ott.

Aside from standing out as one of the few active players on this list, Donaldson holds an exceptionally fascinating place among this collection -- for he accomplished virtually nothing beforehand. To give a sense of how much he differs, a couple of items can be offered:
• Among the 24 players, nine had their debut seasons come as teenagers, six others debuted in an age-20 season and six began in an age-21 or age-22 season. Only Donaldson, Wade Boggs and Chase Utley got a later start (each in his age-24 campaign).
• The 23 players not named Donaldson averaged 38.4 WAR from their debut seasons through their age-26 campaigns. Donaldson produced a value of 1.2. The next two closest to the 2015 AL MVP come in at 9.8 (Utley) and 17.9 (Boggs).
Put simply: The game has never witnessed a player quite like Donaldson -- one who produced so much in his late 20s after doing so little up until that point.
Donaldson's value -- and how extraordinary it is considering what he did prior to his sudden ascendance -- can also be viewed from the single-season numbers he has produced since the start of 2013. In the modern era, Donaldson (with WAR figures of 7.7, 7.3, and 8.8) is one of 46 players to have at least three 7.0 WAR campaigns in his seasons as a 20-something. Of these 46, Donaldson is one of three to have his first in his age-27 season, and you have to go back more than 80 years to find anyone quite like him in this regard. The other two:
• In his age-27 season in 1901, future Hall of Famer Honus Wagner had a 7.1 WAR. Prior to that, Wagner (who debuted as a 23-year-old in 1897) produced a total of 17.2 WAR, which ranks as the eighth best for any player from 1897-1900. In other words, unlike Donaldson, Wagner was already one of the best players in baseball before taking things to another level.

• In his age-27 season in 1929, future Hall of Famer Al Simmons had a 7.9 WAR. Prior to that, the Athletics outfielder (who debuted as a 21-year old in 1924) accumulated 23.5 WAR, had three top-five finishes in MVP Award voting, and in 1925, collected 253 hits (still the fifth-highest total of all-time) while batting .387. Again, unlike Donaldson, Simmons was already a star.
To be fair, just being a late-bloomer does not make Donaldson unique. In fact, two of his Toronto teammates could be also be described as such. Jose Bautista did not put up a positive WAR until he managed a 2.9 mark in 2009, at the age of 28. He followed that up with 6.9 WAR in 2009, and he has averaged 5.4 WAR in the five seasons since. Edwin Encarnacion did not top 1.6 WAR until he produced a 5.0 mark in 2012 at the age of 29, and he has averaged 4.1 WAR over the past three seasons. But as good as those two Blue Jays are, neither of them has had a three-season run that compares to what Donaldson just accomplished.
Donaldson's emergence from non-factor to true superstar gives him a unique niche, with a three-year outburst that compares favorably to some of the game's all-time greats. His career arc is undoubtedly rare and his rise has been fascinating to witness.