As a fan who spent as much time as a child looking at the back of baseball cards (see my profile pic) as the front, it’s been a long and slow process of learning the newfangled statistics available at places like Baseball Savant.
Take batting average. It’s so easy to understand. I divide hits by at bats and I suddenly know exactly how frequently a hitter will get a hit. Easy enough, right?
Look, by now, you know that’s simply not the case. You’re a smart fan — you’re reading my articles, after all! — so, I know that you’re aware of the flaws with standard baseball stats. Even though my understanding of these statistics have changed, what has not changed is my desire to better understand the game I love. Baseball is weird and strange and fluid and somehow both predictable and unpredictable at the same time.
I now spend less time looking at the back of baseball cards and more time trying to learn the new metrics. Weighted (w) stats, like wOBA or wRC+, and expected (x) stats, like xwOBA, simply do a better job of explaining what actually happened on the field, why it happened, and what that means for the future than traditional stats.
In theory, at least. Just as there are pitfalls in interpreting batting average, so are there dangers with advanced metrics. The difficulty is not in knowing what wRC+ or xwOBA are; it’s understanding what they mean.
This is where I find myself in my evolution as a baseball fan, who now has the added responsibility of an audience. I know what the stats say for an individual player, like Paul Goldschmidt. I am still struggling to figure out what they mean for Paul Goldschmidt. It’s a subtle but vital difference.
If you’re willing to join me there — in the uncomfortable dwelling place of uncertainty — then let’s acknowledge that we’re in fine company. MLB franchises, including the Cardinals, are still a long way from perfecting their analytics. If it was easy to interpret and project statistical data, then MLB could just award championships based on spreadsheets. Can’t you imagine it? All of us gathering around our iPads in October waiting for the database to update so we know who gets to hang a banner? Thankfully, such is not the case.
I set out in this article to learn what caused Goldschmidt’s struggles in 2019 and if those struggles were likely to continue. About 1000 words from now you’re going to hear me say, essentially, “I don’t really know” to both questions and we’re all going to have to be okay with that, because anything more than that is probably a fool’s (gold) errand.
What caused Goldschmidt’s struggles in 2019?
Bad puns? Probably. Or maybe it was his massive decline in BABIP — batting average on balls in play. While a player’s BABIP can vary from year-to-year, the median is around .300 for MLB hitters. Since 2015, Goldschmidt’s BABIP has been unusually high, ranging from .382 and .343. In 2019, at age 31, Goldschmidt finally regressed to the median (.303) and that substantial drop in hits on balls in play sank his baseball-card stat line: .260/.346/.476, down from .297/.398/.532 in his career through 2018. This drop showed up with comparable collapses in weighted production stats like wRC+ and wOBA.
Why did it happen?
Goldy’s batted ball profile helps shape the story. There is a strong correlation between line drive rate and BABIP. Goldy experienced only a slight drop in line drives — .5% decline — from his career rate. That corresponds with a decrease in ground balls and an increase in fly balls. Slightly fewer line drives and ground balls and slightly more fly balls would lead to a small dip in batting average on balls in play (and also a potential increase in HR’s, which Goldy experienced), but it doesn’t account for the massive drop Goldschmidt experienced.
In the golden age of yesteryear (like 2018), I would have argued that a drop in BABIP without a correlating drop in line drive rate would strongly indicate bad luck over the course of a season. Bad luck today is sure to be good luck tomorrow, right? Right! So, Goldy is destined to come up... uh... golden in 2020! If that sounds good to you, then you’ve hit pay dirt. Just stop reading now.
Personally, I’m not at all satisfied with that interpretation. We’ve barely scratched the surface of the information available to us now.
Baseball Savant and its Statcast data tell us that even though Goldschmidt’s overall line drive percentage was relatively stable compared to his career, the quality of his contact lowered. Since 2017, Goldschmidt’s average exit velocity has dropped 1.3 mph. His hard hit % has fallen nearly 5%. He still excels in both categories relative to the rest of the league, but he’s not quite as elite as he used to be:
A declining exit velocity is a pretty significant hit to the bad luck theory. It doesn’t get any better when we consider the types of pitches Goldschmidt faced, particularly fastballs, and what he did with them. In 2019, Goldy experienced a massive drop in actual and expected production against fastballs — .349 wOBA/.369 xwOBA. While those numbers don’t seem that bad by themselves, they’re glaring when placed in the 24-karat context of his sterling career. Here are Goldy’s wOBA/xwOBA against fastballs since 2015:
2015 - .446/.430
2016 - .410/.388
2017 - .453/.455
2018 - .414/.432
2019 - .349/.369
Goldschmidt’s actual and expected production against fastballs dropped just over .060 points from 2018, and almost .100 from 2017. That’s a gigantic loss of production against a pitch type that Goldschmidt saw 58% of the time. Exit velocity is already factored into the above stats, but it’s worth highlighting. During this time span, Goldschmidt twice had exit velocities over 93 mph against fastballs. In 2019, that fell to 90.4 mph.
Remember, we started this process by trying to explain Goldy’s huge BABIP drop despite a relatively consistent line drive rate. With a sluice full of data, I went back to Fangraphs and re-sorted his line drive rates by pitch type and there was the shining nugget for which I have searched. Goldschmidt’s line drive percentage against fastballs dropped nearly 8% from his career rate, 28.5% career to 20.6% last season. That represents a 14% drop over 2018.
What caused Goldschmidt’s BABIP — and, correspondingly, most of his other stats — to drop so precipitously? Goldschmidt did not turn fastballs around with the same authority as he has in the past. The result was fewer hits, far fewer doubles, and a sharp drop in overall offensive production.
Are Paul Goldschmidt’s struggles likely to continue?
But, why? Why the drop in exit velocity? Why did he suddenly have so many fewer line drives and less thump on fastballs when Goldschmidt has thrived on them? And how does it fit with moments like this (at least three of these were hit off hard fastballs)?
We’ve dredged up a pretty good pile of information about what happened to Goldschmidt. But, I’m not sure we’re really any closer to knowing what it all means for his future. So, I sought a little help. I turned to fellow Birdo John LaRue, who has been setting me on the analytical straight and narrow since at least 2005, when I was blissfully and ignorantly lauding the Cardinals’ signing of Juan Encarnacion. John gave me a combination of hunches and no small amount of data crunching — including barrel % and its connection to Goldschmidt’s wOBA. We talked about the change in Goldy’s production over the course of the season (see below).
Through it all, here’s where I am landing: while we might have a clearer picture of why Goldschmidt struggled in 2019 (collapsed BABIP caused by trouble with fastballs, particularly in the first half of the season), there are too many factors at play to make a definitive statement about what that means for his immediate future.
Just consider all the changes that Goldschmidt experienced in 2019. He played 81 games in offense-suppressing Busch stadium instead of hitter’s haven Arizona. He had a new hitting coach, with a new approach to in-game strategy and in-the-cage swing adjustments, new strength and condition programs, and a whole new set of pitchers to face in the NL Central.
Consider also the progression of Goldschmidt’s season. Goldschmidt struggled to a .330 wOBA in the first half but bounced back to a .365 wOBA and an improved line drive rate after the break. Is this much ado about a simple early season slump?
What about aging concerns? Goldschmidt is now 32. There is a well-established correlation between age and exit velocity decline, though most models would not project a decline as significant (in % change) or as rapid (speed of change) as what Goldschmidt displayed between 2017-2019.
Lastly, there are volatility concerns in the data itself. Line drive rates against four-seam fastballs is not exactly the most stable data sample.
All of this is enough to make my head spin!
But, you know what? That’s okay! This is a complex and beautiful game. Sometimes seasons like the one Goldschmidt had with the Cardinals can’t be easily explained by a guy with a laptop who writes for an internet blog. Neither can his future be accurately projected by said guy.
What happened to cause Goldschmidt’s bad season? A bunch of different things happened, most of them related to struggles against fastballs.
Will his decline continue? I don’t really think it will. But, I also don’t know that he’s going to return to his MVP-caliber self. The safe bet is somewhere in between.
STEAMER thinks that Goldschmidt’s second half is what we should expect going forward. They give him a .323 BABIP, which is good for a .273/.369/.494 slash line, .362 wOBA and a 126 wRC+. That’s right in line with Goldschmidt’s expected wOBA (xwOBA) from 2019 - .361. That projection seems to have the right amount of optimism in Goldschmidt’s ability to rebound against fastballs and the right amount of pessimism in his ability to rediscover the much-higher-than-the-median BABIP he displayed in his youth.
There you go. We’ve panned for Goldschmidt’s lost production and struck uncertainty. And bad puns. I’m anxious to see how you deal with this data in the comments below! Maybe you can find something shiny in the brick of slag I’ve left for you! (Bonus points if you can mine up your own Goldy puns! Hopefully that’s a karat-on-a-stick to get you started...)
For additional reading: Fangraphs’ article from 2018 about Goldschmidt’s struggles against high velocity fastballs.