There's something of an old joke in baseball analytics circles that goes like this:

"Q: How long into the season must you wait before it's no longer too early to look at the Wins Above Replacement leaderboards?"

"A: When Mike Trout is atop them."

The humor is obvious: When the best player in baseball is atop the list of the catch-all metric that purports to show the best players in baseball, then perhaps enough baseball has been played that you can try to take some meaning from WAR.

Friends, today is that day. It's only April 8. Trout's Angels have played only about six percent of their season. But when you look at the FanGraphs Wins Above Replacement leaderboards, you'll see the only name that matters atop the list. The best player in the game is where you expect him to be.

2019 Wins Above Replacement leaders, FanGraphs

1.2 -- Trout, Angels / Cody Bellinger, Dodgers
1.1 -- Tim Beckham, Mariners
0.9 -- Anthony Rendon, Nationals / Christian Yelich, Brewers

Now, the caveats here ought to be obvious, in that a handful of teams haven't even had a home game yet, that even Trout can't keep up a .581 on-base percentage all year long, that FanGraphs hasn't even rolled in defensive value yet, making this a measure of hitting, base running, and position. It's so early.

Still, there's signals here. Trout just homered five times in four games. Beckham is a shortstop hitting .400/.489/.825. Bellinger, Rendon, and Yelich are established stars hitting a combined .418/.500/.964. There's at least something to this.

That being the case, and because Trout is in his prime at 27 years old, and coming off his best-ever hitting season -- his .460 OBP was a career high, and his .628 slugging basically equaled 2017's career high, leading to career-best marks in OPS, OPS+, and wRC+ -- and because he's Literally Mike Trout off to this start, you can at least ask the question. You can ask: Is this going to be the year that ends up being the best of all time?

It's not hyperbole to ask. Not with his track record, and not with facts like this one ...

... and this one.

So, what does he need to do to get there?

A lot, actually.

What is the best season of all time?

Conveniently, both FanGraphs and Baseball-Reference share agreement on what was the best season ever, settling on Babe Ruth's 1923. (FanGraphs says 15 WAR, Baseball-Reference says 14.1) That year, Ruth hit .393/.545/.764 with 41 homers, about 10 percent of the entire total of the American League, but his value was boosted by his defense, as he set career bests in innings and putouts, as well as posting his second-most assists.

Ruth, according to FanGraphs, has the only four seasons of 13 WAR or more. Only 25 seasons have made it to 11 WAR or more, and only three of those have come in the last four decades, all belonging to Barry Bonds. Trout's best mark was 10.2 WAR back in 2013, but given what we know about how little importance a tenth of a point of WAR really carries, he's essentially tied that mark in 2012, 2016, and 2018.

Now, if we really wanted to go nuts with 'on pace' -- in the same entertaining-but-not-in-any-way-realistic fashion that Bellinger is 'on pace' for 97 home runs -- we could look at Trout's 1.2 WAR per 10 games pace, do some quick math, and come up with 19.2 WAR. If Trout continues to have one of his best weeks over and over and over again, he'd have the best season ever, by a decent gap.

That, of course, is not going to happen. Instead, let's consider those first 10 games of the season 'banked.' That is, let's give him those 1.2 WAR over 10 games, and let's think about only what might happen over the remaining 152 games. Let's start that season over, which isn't as crazy as it might sound; remember, the Red Sox and Cubs have yet to play in the home whites.

We don't know, obviously, how it's going to play out. We don't know what he'll suddenly improve out of nowhere this year, just like he decided to improve his defense last year and then did. But we've seen enough of Trout over his nearly 5,000 career plate appearances to know what he's capable of.

Let's play a fun game of 'what if?' We'll assume he'll get into 150 games this year, because no one plays 162. The fun thing here is that even Trout's 'worst outcome' is going to be really, really good.

What if he has his worst season?

Here's the thing: Trout's 'worst' season was 2017. He finished a career-low fourth in the American League MVP balloting -- how disappointing! -- by hitting 'only' .306/.442/.629 with 31 homers, and, thanks to some subpar-by-his-standards defense, merely 6.9 WAR. Of course, he did that in only 114 games, due to a thumb injury.

Were we to apply that pace to 140 more Trout games, we'd get: 8.5 WAR. Add that to his 1.2, and that's 9.7 WAR. It's unfair that he's this good.

What if he has his average season?

Trout's 'average' season is a .307/.417/.576 line and 9.2 WAR. Due to the injury-shortened year, that's actually his pace over 140 games as well, so that plus the 1.2 WAR: 10.4 WAR.

What if he has his projected season?

Trout was projected to put up an 8.6 WAR season; projections are notoriously conservative. That WAR-per-game over 140 additional games is 8.3 WAR, so plus the current 1.2 WAR, that's 9.5 WAR. That's disappointing! Projections aren't supposed to project historic greatness, though.

What if he has his best season?

His 2012 and 2013 seasons were essentially tied in this regard, at 10.1 WAR and 10.2 WAR. Realize that in the last half-century, since the dawn of divisional play in 1969, only seven men have hit that mark aside from Trout -- Bonds (five times), Joe Morgan, Cal Ripken Jr., Mookie Betts, Buster Posey, Rickey Henderson, and Alex Rodriguez -- and only Bonds and Trout did it more than once.

We'll take the 2012 pace, because he did it in just 139 games, having spent the first month of the season in Triple-A. Conveniently enough, that's basically the 140 games we're looking for; add the 1.2 he's banked, and that's 11.3 WAR.

What if he has a better season than his best?

That sounds crazy. Trout is already the best non-Bonds player you'll likely see, and it's not fair to expect more.

Except ... he has been giving more. His offensive performance has increased in each of the last five seasons. As we noted above, his defense improved last year. It's not improbable his best season hasn't been seen yet.

Now we're into full back-of-the-envelope math here, but if we take last year's 9.8 WAR, boost his offense enough to put him on an 11 WAR pace, then first add the 1.2 WAR, we're maybe looking at a 12 WAR season. It's insanely, historically good. It's still not close enough to Ruth.

You may be saying now that the hot start hasn't changed his expected outcomes that much, and that's true. (Don't forget also that his 'hot start' had a different feeling before the Rangers came to town, when he was hitting 'only' .294/.480/.412 without a homer in his first six games.) It's hard for a few games of damage to meaningfully change a full-season projection. All of this is in the 9-to-11 WAR range.

But mostly, it's because this has been a nice few days for Trout, not an otherworldly outlier like when Kendrys Morales homered in seven consecutive games last year. He's maybe not always this good; he's not that far off, either. He is very legitimately one of the best players in the history of the game. It's why you can even talk about "how can he match the mighty Ruth?" without sounding ridiculous. They belong in the same sentence.