But really, even those lofty honors aren't enough to accurately describe what we're witnessing. Harper isn't just one of the best players in the game coming off one of the best seasons we've ever seen. He's on track to be one of the best of all time.
Those are some pretty bold statements to make without backing them up, so let's do exactly that. To the data!
Because Harper's 2015 season was even more dominant offensively than you think it was.
Weighted Runs Created Plus (wRC+) is a pretty handy stat to have around, because it's adjusted for park and league, so it can be used to compare players across eras. Since it sets 100 as league average for that season (think Martin Prado or Marlon Byrd in 2015), it's easy to quickly understand as a hitter being a certain number of percentage points above (or below) league average.
Harper just finished up a season with a 197 wRC+, or "97 percentage points better than average." If you're thinking that sounds pretty good, well, you'd be right. Since the dawn of modern baseball in 1901, there have been 12,426 qualified hitter seasons. Only 38 -- that's 0.003 percent (!) -- were better. And since inner-circle legends like Ted Williams, Babe Ruth and Barry Bonds had multiple such seasons, there are actually only 13 individuals in the past 115 seasons of baseball to outperform what Harper just did.
Let's make that a bit more visual. The chart below shows those more than 12,000 seasons, and you can see that thousands of them are clustered around league-average (100 wRC+). Harper's 2015 is an extreme outlier:
For a comparison, Harper's 2015 comes in very comparably to two of the most storied seasons of all time:
There are different ways to get there (Brett had more hits fall in, but fewer homers), yet you get the point. This sort of season just doesn't happen, until it does. And when it does, you remember it.
Because it's hard to be this good, this young, and not end up being a legend.
Since this was one of the 40 best hitting seasons ever, you're probably assuming it's the best by someone as young as Harper, who just finished his age-22 season, and you'd be close, with only Williams' iconic .406 season in 1941 coming out ahead by wRC+. Along with that Williams year and Stan Musial's 1943, Harper just became one of only three players ever to lead baseball in both OBP and slugging at 22 or younger.
By now you've noticed that we've dropped some names, the kind of names that seem more like gods of the sport than actual humans who once played. That being the case, glance at this list of the 11 men to accumulate at least 17 Wins Above Replacement (WAR) through age 22 over the past century of baseball, and realize the company Harper is in:
Point is, other than serious injury or whatever happened to Andruw Jones, you don't put up this much performance at this age and not end up with a plaque in upstate New York. You just don't. (Related: Mike Trout is on an unspeakably great path himself.)
If there was disappointment in Harper's first few years, it's because he was such a massively hyped prospect who came up at such a young age that a few seasons of merely above-average production didn't seem like enough. But it's easy to forget just how young he was; after all, despite making his pro debut in 2010, he never faced a pitcher younger than he was until just this past June, when he faced the Yankees' Jacob Lindgren. He's younger than Trout, Noah Syndergaard, Mookie Betts, Xander Bogaerts and Kris Bryant. Harper is younger than just about everyone -- and better, too.
Mike Petriello (@mike_petriello) is an analyst for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.