New York Yankees outfielder Aaron Judge went 4-for-4 with two home runs and a double against the Orioles on Sunday, bringing his batting line up to .344/.450/.718 for the season. Call that Bryce Harper’s 10-win MVP campaign from 2015, plus another 69 points of slugging percentage. Since the strike, only four players have slugged .700 in a season: Mark McGwire, Sammy Sosa, Barry Bonds — with all the baggage they come with — and Larry Walker, who did it twice for the Rockies while Coors Field was at its Coors Fieldiest.

As we hit mid-June, most of the other early-season freak shows have cooled off: Mike Trout and Freddie Freeman got hurt. Eric Thames is still hitting .256/.396/.569, which is great, but in a stunning reversal from six weeks ago, it’s a statistical profile you’d recognize as belonging to a human being. And yet here the 25-year-old rookie is, hitting balls out of the park at a record-breaking 121.1 miles per hour and leading the league with 21 home runs.

So, how did this happen?

Judge was a first-round pick, but a late first-rounder, 32nd overall out of Fresno State in 2013. He was long a top-100 prospect, but never a top-10 prospect. He was flat-out bad in 95 plate appearances last year: .179/.263/.345. And if the Yankees thought he was going to do this, they wouldn’t have floated him in trade discussions.

The thing about that trade rumor is it looks bad now because Judge, Luis Severino, and Gary Sánchez have all panned out so far, while Jason Heyward and Melvin Upton both got substantially worse after leaving Atlanta. But at the time nobody would’ve expected this from Judge; the reason we’re treating this season as remarkable is that it is, in fact, remarkable. Prospects like Judge — or rather, prospects of Judge’s quality, since there aren’t really prospects like Judge — don’t turn into big leaguers like Judge very often.

Even though we’re in mid-June, some of the explanation still rests in this being a small sample. Judge has batted 249 times this year, which doesn’t constitute enough of a sample to prove that he’ll hit like Walker in Coors Field for the rest of his career. Good full seasons like this don’t happen very often, but good partial seasons like this happen relatively frequently. For example, in 1957, the Braves brought up Bob “Hurricane” Hazle, an outfielder of about the same age and experience level as Judge now, and he hit .403/.477/.649 in 155 plate appearances. The next year he hit .211/.302/.281, and by 1961 he was out of baseball. Since the strike, there have been 41 cases in which a batter has slugged .700 in either the first or second half of the season (minimum 200 PA). Judge is one extended slump from his season looking merely MVP-caliber instead of historic, and he’s still got time left to slump.

But saying “this isn’t going to last” is no fun and sells Judge short for the improvements he’s made over the past five years. Here’s Judge playing in the Cape Cod League in 2012, after his sophomore year at Fresno State.

At this point in his college career, Judge had hit only six home runs in almost 400 at-bats, and it’s easy to see why. That version of Judge was knock-kneed, and he transferred his weight to his front foot early. His swing was long but also somehow oddly tentative, like he was self-conscious of his size and was afraid of hurting the baseball. He looks like a baby wildebeest.

Today’s Judge has a shorter, faster swing, and he’s hitting with exactly the kind of confidence you’d expect from a guy with 21 home runs on June 11. He’s also filled out, adding almost 30 pounds since draft day. Even men who were built like Andre the Giant when they were young tend to get bigger and stronger from age 20 to age 25.

Except, almost every worthwhile position player prospect builds up his body and refines his swing mechanics as he moves from college to the pros. That’s what you expect to happen. But when normal development runs into a player as big and strong as Judge, you get balls coming off the bat at record speeds. We’re at a point — not just in baseball, but across most sports — where impossibly large athletes are moving in ways we wouldn’t expect men that size to be able to move. Kris Bryant is huge for his position, and so is The Mighty Giancarlo Stanton, but while Judge, like those guys, is an enormous power hitter who hits big home runs, he has almost 40 pounds on TMGS and more than 50 on Bryant. TMGS and Bryant are the size of 3–4 outside linebackers, but Judge is a big breakfast from being the size of an offensive tackle.

Judge is definitely the biggest everyday position player in MLB history, and if he doesn’t have the most power in the game, he’s up there. In that respect, “Where the hell did Aaron Judge come from?” has a simple answer: He’s what happens when a normal MLB power hitter is about 15 percent bigger.

We’re not fascinated by his batting line, or even necessarily how many home runs he’s hit; it’s how hard they come off the bat and how far they travel. Judge is the perfect breakout star for MLB’s tracking novelty, Statcast, which duly records the exit velocity of every home run. Judge’s 121.1 mph home run was the fastest of the “Statcast era,” which is an awfully grandiose way to say “since 2015,” but it only adds to Judge’s mystique.

From his physical tools to the adjustments he’s made in the pros to the combination of time, place, and team, no individual part of Judge’s ascent to stardom is that unlikely on its own. But for all of those factors to align, well, we’ve never seen anything quite like that before.

An earlier version of this piece included the wrong Upton brother; it was Melvin Upton, not Justin Upton.