The Rangers' strong start this season isn't just surprising, it's historic.

Through their first 40 games, the Rangers outscored their opponents, 254-157, while going 25-15.

Prior to 2023, only 13 teams dating back to 1901 posted a run differential of +97 or better through 40 games, per Stathead. Among those teams, 11 made the postseason, and nine went on to win the World Series.

It’s been more than 100 years since the last time a team (Cleveland in 1921) missed the playoffs after recording a run differential at least that high through 40 games.

The fact that the Rangers have done this after going 68-94 (.420 winning percentage) a year ago makes it all the more amazing. Of the 13 teams that started off a season with a run differential of +97 or better through 40 games from 1901-2022, none had a lower winning percentage than .568 the previous season.

As the Rangers prepare for a tough test against the Braves starting Monday, here are six reasons to buy Texas as a legitimate postseason contender. (All stats are through Saturday's games.)

1) Their lineup has been a juggernaut -- without their best hitter

Considering all the money the Rangers spent on pitching in the offseason, signing Jacob deGrom, Nathan Eovaldi, Andrew Heaney and Martín Pérez in free agency, it seemed likely that their postseason hopes would largely depend on the performance of their rotation.

However, the team’s offense is the biggest reason for its strong start. The Rangers entered Sunday’s series finale against the A’s averaging 6.23 runs per game, the most in MLB.

They’ve done that despite losing star shortstop Corey Seager to a strained hamstring after 11 games.

After more than a month on the sidelines, Seager is expected to come off the injured list this week. He'll return to a .359/.469/.538 slash over 49 plate appearances this season.

Texas has gotten positive contributions from a wide range of players -- of the 12 Rangers hitters with at least 50 PAs, nine have an OPS+ of 105 or higher. The Rays (10) and Rangers are the only clubs that have more than seven such hitters.

2) Jonah Heim is having a moment

Heim was a solid contributor for the Rangers in 2022, pairing elite framing skills with a bat that was close to league average (97 OPS+), but it’s safe to say no one saw this coming.

The switch-hitting catcher, who is with his fourth organization after being traded three times between August 2016 and February 2021, has broken out at the plate, producing a .319 average, six homers, 29 RBIs and a .925 OPS over 33 games, with the underlying metrics to match.

Heim doesn’t have a lot of swing and miss in his game despite his aggressive approach, and he’s made meaningful adjustments to hit for more power. Heim’s pull rate and hard-hit rate are both up 4.8 percentage points and his ground-ball rate has dropped 8 points from 2022. As a result, only one hitter has pulled more hard-hit balls in the air than Heim in 2023.

The 27-year-old is still doing good work on defense, too, tying for eighth among catchers in called-strike rate on borderline pitches and tying for second in framing runs saved.

3) Their young players look like keepers

In addition to Heim’s surprising performance, the Rangers have gotten unexpected contributions from a trio of 25-and-under position players: third baseman Josh Jung, utility infielder Ezequiel Duran and center fielder Leody Taveras.

Jung, who entered this season ranked as MLB Pipeline’s No. 34 prospect, has socked eight dingers and slugged .456 over 159 plate appearances. Jung’s 105 OPS+ is a significant upgrade over the team’s third-base production in 2022, when Texas’ third basemen tied for second-to-last in the Majors with a 69 OPS+.

As the Rangers’ most-used third baseman in 2022, Duran (82 OPS+) contributed to that poor figure. However, he’s been much better this season, filling in at shortstop after Seager’s injury and slashing .296/.327/.491 (124 OPS+) overall. Duran has increased his average exit velocity by 5.4 mph and his hard-hit rate by 20.1 percentage points compared to 2022.

Taveras (123 OPS+) is hitting well, too, and he’s made a positive impact patrolling center field. The 24-year-old ranks in the 95th percentile in sprint speed and average outfielder jump, the 96th percentile in arm strength and the 89th percentile in outs above average.

4) Marcus Semien is heating up

After a third-place finish in the AL MVP race with the Blue Jays in 2021, Semien signed a seven-year, $175 million deal with the Rangers and proceeded to hit .193 with no home runs in his first 43 games with the team.

However, since May 28, 2022, the day he recorded his first Rangers homer, Semien has produced 33 homers, 103 RBIs, 116 runs, 25 steals and an .827 OPS over 155 games, tying for second in the Majors in wins above replacement (per FanGraphs) during that span.

Slow starts have become typical for Semien in recent years, but the veteran infielder has avoided that in 2023. After going 11-for-52 (.212) in his first 12 games, Semien has slashed .327/.441/.558 with six homers, 22 walks and 26 RBIs in his past 27 games, setting the tone atop the order.

5) Eovaldi is stepping up ... and so is Dane Dunning

Most of the Rangers’ offseason pitching moves haven’t worked out well so far -- deGrom is sidelined with right elbow inflammation, Heaney owns a 5.25 ERA, Pérez has some concerning peripherals and Jake Odorizzi is out for the season after undergoing right shoulder surgery.

But Eovaldi has been the exception, recording a 2.70 ERA over eight starts. The right-hander has taken on the mantle of staff ace in the wake of deGrom’s injury, tossing 25 2/3 scoreless innings in his past three trips to the mound.

Meanwhile, one of the pitchers who was displaced from Texas’ rotation by the club’s myriad of new faces suddenly finds himself back in a prominent position.

After opening this season in the bullpen and notching a 1.77 ERA over 20 1/3 innings in April, Dunning has rejoined the starting staff following deGrom’s injury and pitched well over his first two starts (1.64 ERA).

Dunning isn’t missing many bats, but he’s limiting damaging contact with the help of his cutter, which he’s throwing a career-high 29% of the time. Opposing batters have gone 2-for-23 (.087) with no extra-base hits against the pitch in 2023.

6) They have an ace in the hole

deGrom will likely be sidelined into June with his injury, but if he can make it back healthy, he could provide a substantial boost for Texas around the time other pitching-needy contenders are beginning to consider their options on the trade market.

The Rangers won all six of deGrom's starts before his IL stint, as the two-time Cy Young Award winner recorded a 2.67 ERA with 45 K's in 30 1/3 innings.