Not all stats are created equal. Some, like home runs, batting average or RBIs, are mainstays of the game that offer a baseline look at a player’s production. And while those stats are important and necessary, they sometimes don’t tell the whole story when it comes to a player’s production.

That’s where expected weighted on-base average (xwOBA) comes in. It’s an all-encompassing stat that evaluates a hitter based on strikeouts, walks and quality of contact (i.e. exit velocity and launch angle), helping filter out factors such as defense and luck.

Here’s a look at seven hitters who have improved their xwOBA significantly this season – and what’s behind that surge. For additional context, this year’s MLB average xwOBA is .323.

Note: statistics are through Sunday’s games.

Jonah Heim, Rangers
xwOBA gain: 82 points (to .373)

Coming into this season, Heim was known more for his defense, recording 20 catcher framing runs in his first two seasons with the Rangers while only hitting .215 in 735 plate appearances. Now, he’s looked like one of the best offensive catchers in baseball, and has the fifth best slugging (.486) among MLB backstops this season.

As a switch-hitter, Heim has spent the year hitting for average from the left side (.424 average in 33 at-bats) and power from the right side (five home runs in 109 at-bats). He’s also figured out how to hit fastballs, batting .288 against heaters, up from .220 and .186 over the previous two seasons. Not bad for a guy who was once the player to be named later in a trade.

Joey Gallo, Twins
xwOBA gain: 73 points (to .368)

While Gallo will always be a bit of a polarizing player due to his extreme affinity for the three true outcomes, there’s no denying the positive impact he’s had on the Twins this year.

Gallo’s strong start to the season can be attributed to a couple of factors. He’s pulling the ball more than ever (65.2% pull rate), striking out less (career-low 33.6% strikeout rate) and hitting it harder than ever (career-high 60.6% hard-hit rate). He’s also found success as the team’s leadoff hitter in a bit of an unconventional move that’s paid off so far for manager Rocco Baldelli.

Patrick Wisdom, Cubs
xwOBA gain: 64 points (to .359)

The bad news about Wisdom’s game is that he has the highest strikeout rate among qualified hitters (37.6%). The good news is that he’s excelling at just about everything else, ranking in the 94th percentile in average exit velocity and the 98th percentile in hard-hit rate – both of which are significant improvements over his 2022 numbers.

Striking out will always be a part of Wisdom’s game (this is his third straight season being in the first percentile in strikeout rate), but he’s been able to make up for that this year with the fifth-best barrel rate in all of baseball. In 2021, Wisdom hit .231 with 28 home runs to finish fourth in the NL Rookie of the Year voting. If he keeps up on his current trend, he should easily eclipse those numbers.

Austin Hays, Orioles
xwOBA gain: 62 points (to .360)

Last year, Hays had a strong start to his season when he hit .297 in his first 46 games. He’s been even better this year, hitting .311 with five home runs and 16 RBIs through his first 42 games.

Along with ranking in the 66th percentile in hard-hit rate, Hays is getting better results when putting the ball in play. He’s only hit four popups this season after hitting 44 last year, which was tied for the 13th most in baseball. He also is doing a much better job of getting to fastballs this season, batting .395 against heaters – more than 150 points higher than last year.

Elias Díaz, Rockies
xwOBA gain: 60 points (to .334)

Another defense-first catcher who is beginning to find his footing offensively, Díaz has raised his batting average by nearly 100 points compared to last year, and is on pace for this first season with an OPS+ above 100 (league average) since 2018.

The biggest key for Díaz is that he’s been able to make more contact, as evidenced by him cutting 4 percentage points off of last season’s strikeout rate. Interestingly enough, Díaz’s splits this year have been in stark contrast to his career numbers: The right-handed batter is batting .360 off right-handed pitching and only .219 off left-handed pitching – the exact opposite of his career numbers (.241 off right-handed pitching, .269 off left-handed pitching).

Yandy Díaz, Rays
xwOBA gain: 59 points (to .424)

Coming into this season, Díaz was a guy who profiled as an on-base machine who hit the ball hard but not for power. That’s changed this season, with the 31-year-old leading the American League in batting average (.329) and on-base percentage (.429), along with leading all of baseball in OPS+ (192).

The biggest difference for Díaz has been his ability to keep the ball off the ground, cutting his ground-ball rate from 50% to 46.8% while raising his fly ball rate from 19.6% to 27.4%. That’s helped boost his barrel rate, which has gone up to 12.9% this season after only being 4.8% last season. He’s already tallied 16 barrels this year (which is four away from his total from last season) and is still hitting the ball hard, ranking in the 98th percentile in hard-hit rate and setting a new career-high with a hit that had an exit velocity of 114.5 mph.

Jack Suwinski, Pirates
xwOBA gain: 59 points (to .366)

Despite hitting 16 home runs in 106 games last season, Suwinski finished his rookie year with an OPS+ of 99 (one point lower than league average), which was due in large part to his 6th-percentile strikeout rate.

And while Suwinski currently has a strikeout rate in the 8th percentile, he’s been able to put together a better all-around season this year thanks to an elite chase rate (98th percentile), a stellar walk rate (95th percentile) and a high barrel rate (92nd percentile). At only 24 years old, Suwinski has all the makings of a star for the Pittsburgh Pirates, so long as he’s able to keep getting better.