At 40-26, the Oakland A’s have the second-best record in the Majors — two games back of the San Francisco Giants. But by almost every other reasonable measure, the A’s are the best team in baseball. And it’s not particularly close.

By the park- and league-adjusted offensive stat OPS+, the A’s offense is tied with the Toronto Blue Jays for tops in the Majors at 111. By the similarly adjusted pitching stat ERA+, the A’s stand head and shoulders above the rest of the league.

They lead the American League in Fielding Independent Pitching with a 3.56 mark, and pace all teams in defensive efficiency — the rate at which batted balls are turned into outs.

Simply put, the Oakland A’s have the Major League’s best offense, defense and pitching staff. That’s a very good way to win ballgames, and so, not surprisingly, the A’s have outscored their opponents by an astonishing 130 runs through Wednesday’s play.

The next best team, the cross-bay Giants, has outscored its opponents by 53 runs. Run differential is arguably a more useful way to predict a team’s long-term success than its record after only a couple of months.

And by run differential, the A’s look like they could be one of the best teams of all time.

At MLB.com on Wednesday — before the A’s beat the Angels, 7-1 — Matthew Leach put Oakland’s early-season dominance in context:

Since 1903, the year of the first World Series, 25 other teams have begun a season with a run differential of at least plus-124 through their first 65 games (all historical data according to BaseballReference.com). Since 1940, there are nine other teams, and the list reads like a who’s-who of some of the greatest teams in modern times….

(In) the last 35 years, only three teams have matched or equaled the A’s start. And they are three of the greatest regular-season teams of that time span: the 116-win 2001 Mariners, the 114-win 1998 Yankees, and the 106-win 1998 Braves. That’s it. That’s the entire list of teams since 1980 that have outscored their opponents by as much as these A’s over a season’s first 65 games. Those are also three of the four teams in that span to win 106 or more regular-season games (the 1986 Mets are the other).

By “Pythagorean winning percentage,” a stat developed by Bill James to estimate teams’ records based on their run differentials, the A’s have been unlucky to have only a 40-26 record on the season. The stats show that with normal fortune they’d be around 47-19, which would put them on pace for a 115-win season.

Even if they’ve somehow underperformed to the second best record in the Majors, the A’s would be expected to finish with 108 wins if they can maintain their extraordinary run differential through the remainder of the regular season. That’d be the highest total since before the turn of the millennium.

Since they’re the A’s — still run by Moneyball hero Billy Beane — it’s worth nothing that they’re doing this with one of the lowest payrolls in the league. Their $77.8-million roster makes less than a third of the Dodgers’, and three more teams — the Yankees, Phillies and Red Sox — have more than twice the A’s payroll.

Those four teams, combined, have been outscored by 25 runs this season.

And true to form, the A’s are winning behind a bunch of unlikely stars that are still hardly household names. By WAR, their best position player has been Josh Donaldson, a converted catcher who didn’t become a big-league regular until he was 27 and is now among the best all-around third basemen in the game.

Their second best position player has been Brandon Moss, whom they signed as a 28-year-old minor league free agent before the 2012 campaign after he saw only 32 Major League at-bats with the Pirates and Phillies in the two seasons prior.

The A’s best starting pitcher has been Scott Kazmir, a one-time mega-prospect reduced to starting for the indy-league Sugar Land Skeeters as recently as two seasons ago.

And their best reliever has been Sean Doolittle, who played first base in his first three professional seasons before moving to the mound full-time as a 25-year-old in 2012.