Cubs’ luckiest and unluckiest hitters in 2018 based on batted ball data

Unless you’re smacking the ball clean out of the park, there’s going to be some luck involved as an MLB hitter. You can crush a screaming line drive right to the center fielder or dribble a grounder along the baseline that the third baseman can’t quite handle. Once the ball is off the bat, there’s nothing else to do but run toward first.

The result is that a player’s batting statistics are often part-performance, part-luck. The latter can be a boon to someone who keeps squeaking weak contact between defenders. It can also make someone look worse if they’re watching a surefire home run get robbed. Some players might “hit to the gaps” better than others, but defense always plays an impact in a hitter’s results.

For the Cubs, who rank fourth in the big leagues in runs per game, the luck factor has affected some players more than others. It’s been a group effort to overcome some ups and downs from key names. So entering the stretch run of the season, certain numbers can help give us an idea of who is likely to see their performance improve or diminish in the coming months.

Over at MLB.com’s Statcast, they track all sorts of advanced statistics, including detailed batted ball data for every plate appearance. As a result, they have two statistics that work together:

• WOBA, or weighted on-base percentage, a catch-all offensive statistic that boils all of a player’s batting results into one number
• xWOBA, which uses a player’s batted ball data to estimate what their WOBA should be based on historical precedents

Using these two numbers, we can get an idea of which players’ batted balls are converting into the results you’d expect, and which aren’t. If a player’s xWOBA is significantly better than their WOBA, it stands to reason that their WOBA should improve if they continue generating similar contact. The same goes in the other direction.

Here’s a look at the Cubs’ top 10 hitters for the difference in WOBA versus xWOBA. Players in the negative are underperforming their expected results, while those in the positive are over-performing their expected results.

Let’s run through a few takeaways from this chart.

Anthony Rizzo’s recent breakout isn’t surprising

We’ve seen flashes lately of the Cubs’ star first baseman breaking out of his funk in the leadoff spot, and based on the batted ball data, that should’ve been expected. Rizzo’s numbers suggest he should have a team-high .371 WOBA, but he’s at just .336 this season.

Rizzo’s barrel percentage, which measures batted ball events with an average outcome of at least a .500 batting average and 1.500 slugging percentage, is just 4.4 percent, down from 9.3 percent last season. However, he’s setting career-bests in exit velocity (90.2 mph) and hard hit percentage (42.5 percent), so it’s not like he’s stopped mashing balls all over the park.

This year hasn’t been on the caliber of 2017 for Rizzo, who finished last season in the top four percent of players in xWOBA at .400, but his results have dipped more than expected. As we’ve seen recently, there should be better times ahead.

The rebirth of Heyward

Everyone on the North Side knows about Jason Heyward’s improvement at the plate by now, but it’s still striking to see it born out in the Statcast data. The outfielder’s hard hit percentage has improved from 30.9 percent over the previous two seasons up to 42.5 percent this season. That’s far above the league average of 34.1 percent.

Heyward has similarly seen improvements to his exit velocity, up from 86.4 mph to 88.7 mph, and he’s posting his highest launch angle (11.6) of the four years on record. He’s also cut down his strikeout rate to a career-low 10.8 percent.

Add it all up, and Heyward has not only rebounded from the woes of his first two seasons with the Cubs, but he’s playing even better than the .285/.350/.430 line he’s posted. The resurgence is far from a fluke with a .338 WOBA and .360 xWOBA. That’s good news given he’s owed over $100 million through 2023.

Albert Almora Jr. is due for major regression

Now let’s get to the bad news: Almora is wildly over-performing at the plate based on his underlying data. The outfielder is batting .316 this season, so he’s posted a .339 WOBA, but his xWOBA is a brutal .280, which is in the bottom four percent of MLB.

The issues for Almora are obvious: He’s barreling up just 1.6 percent of his batted balls, which is bottom six percent in the league. His launch angle (8.9), exit velocity (86.6 mph) and hard hit percentage (28.3 percent) are all below average. And he’s never been a player to draw many walks, so he relies largely on making contact to generate offense.

Not everything is bad for Almora – he’s a quality defender and baserunner who impacts the game in other ways – but he’s treading on thin ice with his success at the plate this season. In July, he’s hitting .245/.286/.283, so the downward trend already appears to be in progress.