I experience baseball in many different forms. Writing is obviously one of them. Watching (both in person and on television) is another. Playing doesn’t happen as much as I’d like to, but it’s still one of them. The last one, which has become the most accessible to me, is through data: performance, expected stats, projections, etc. Data serves as a conversation starter or a thought provoker for me, and I rely on it heavily in my writing to tell the story of a player’s triumphs or struggles, especially Statcast data.
When working with Statcast information, it’s important to understand the inputs that create the data points. For example, I know that xwOBA is formulated using a combination of exit velocity and launch angle (and sometimes sprint speed). Perhaps it would be helpful if there were more inputs such as batted ball spin or spray angle, or perhaps it would complicate things. But what is important is that I know those are not included in the formulation — knowledge that I can use when assessing players for whom those inputs could be statistically important. I’m specifically thinking of the profiles of Isaac Paredes and Cody Bellinger.
Neither Paredes nor Bellinger have big power in terms of raw exit velocity, and neither is a batting average king (although Bellinger is over .300 at this moment in time). Instead, they rely on consistent contact to the pull side in the air to make up for their lack of raw power. I have an idea in my head of what a good hitter is. One of my most general criteria is the ability to hit the ball consistently hard, but it’s important to leave wiggle room there so you don’t exclude the edge cases, like Bellinger and Paredes. Both are below the 20th percentile in terms of average exit velocity and below the 10th percentile in HardHit%, but both have ISOs over .200 with double-digit home runs and doubles. That’s unusual, but it brings me back to stressing the importance of spray angle for a certain group of hitters.
Here are the expected and actual statistics on fly balls from Bellinger and Paredes:
Expected vs. Actual Differences
| Player | wOBA | xwOBA | wOBA-xwOBA | BA-xBA | SLG-xSLG |
|---|---|---|---|---|---|
| Isaac Paredes | .628 | .352 | .276 | .144 | .554 |
| Cody Bellinger | .599 | .348 | .251 | .187 | .498 |
This is quite drastic. In fact, it’s historically drastic, but I’ll get to that in a second. Among hitters with at least 100 total batted balls, Bellinger and Paredes are easily the league leaders when it comes to difference between wOBA and xwOBA on fly balls. The latter has a decent margin over the former, and both have a big margin over the rest of the field. You can check out the full list here, but for convenience, the next highest discrepancy is Aaron Hicks at .204. After that, there is a .026-point drop to the next person. The same trend holds for BA and xBA discrepancy, with Bellinger ranking first and Paredes third. And as you would have guessed, the difference holds for SLG and xSLG, with the gap being by far the largest through this lens.
In terms of historical differences, we can go back as far as 2015 (beginning of Statcast era) to see who else has had seasons with similar gaps between wOBA and xwOBA on fly balls. For this list, I’m bumping up the minimum to 150 batted balls to exclude players who were playing limited roles but still include the two main subjects of this piece. Here are the top 10:
Largest Expected vs. Actual Differences Since 2015
Right off the bat, we see the top two came from the shortened 2020 season. Two more come from Brett Gardner and Jose Altuve, each of whom have/had friendly home park pull-side short porches that were a huge help. Then the other non-Bellinger and Paredes seasons were all partial years. It’s difficult to do this over a full season and prove that it’s a sticky skill, but Paredes’ repeat performances last year and this year are very compelling.
Paredes is a unique hitter in his own right and deserves some solo attention. For the second consecutive year, he is running roughly top quartile strikeout and walk rates. His whiff rate hovers between the 85th and 90th percentiles, and he launches home runs at a pretty good rate. Consistently hitting home runs with below-average raw power requires excellent swing decisions and an advanced understanding of your swing. You must know what pitches you can pull hard in the air and then consistently attack them in the right zone. Among hitters with at least 10 home runs this season, he ranks fourth in percentage of those hit 105 mph and below. Here are two swings on home runs right down the line. The first is off an inside Justin Verlander four-seamer, and the second is on a low-and-away Luis Castillo slider:
Those balls were hit at 95.1 mph and 96.3 mph, respectively, and though they didn’t travel more than 360 feet, what matters is that they made it over the wall.
You’ll notice that Paredes is as close to the plate as he can get. When he plants his stride foot, he is right on top of the chalk of the batter’s box. This allows him to get his bat on an upward trajectory and catch outside breaking balls in front of the plate and yank them down the left field line. Intuitively, you’d think pitchers should pound him inside with velocity, but the swing against Verlander is an example of how he can pull his hands inside and create a steep path to keep fastballs in this zone in fair territory; either way, it’s not easy to pitch inside in this league.
Paredes’ bat path and swing decisions fuel his extreme pull (50.7%) approach. He doesn’t have much room for error, but if he can continue to hit his hardest batted balls straight down the line, he will keep up this interesting statistical quirk. And I’m sure the Rays know exactly what matchups work best for his approach and swing.
Now, let’s go back to Bellinger. Unlike Paredes, Bellinger has a previous history of being a true light tower power hitter. Between 2017 and 2019, he hit around half of his home runs over 105 mph, but since 2020, that number is well north of 70% and has peaked this year at 83.3%. In hindsight, it’s clear that his current batted ball profile was the best path forward for him after last season, when he hit 79% of his home runs under 105 mph. When you combine his relatively steep angle with his below-average raw power, it makes the most sense for him to work primarily to the pull side in the air, like Paredes, and sometimes to the gaps if he can create the lift.
This year, Bellinger’s Zone Contact% is at a career-high 82.2% thanks to some mechanical tweaks and approach shifting. It’s the only time in his career outside of the 2020 season that he has done this. As you would have guessed, this has led to a career-low whiff rate (22.6%). If your margin for error is thin, you need to understand what pitches best play to your bat path and power, and specifically attack those pitches. Sound familiar? That’s exactly how Paredes goes about it. And these two swings are perfect examples of pitches where Bellinger can catch the ball out in front of the plate against pitchers from both sides:
With trade rumors heating up and the Cubs likely to sell, Bellinger could be on the move to a new team and home park. While I think there is likely a league adjustment coming to respond to his hot streak, he now has a model for what the new version of himself can be, and it sure does look a lot like what Paredes has done with Tampa Bay in the last few years. I think there is some real potential for both of these hitters to continue to have success with their unique profiles, and both serve as a possible model for other hitters going forward who can create consistent lift despite below-average raw power.
