Earlier this week, I examined the batted data on four hitters and I’m diving into four more today. My goal is to see if their breakout or struggles stemmed from normal aging or swing or approach change. Sometimes the change is obvious and other times, it’s murky.

Currently, I’m using five StatCast data points per month:

• Average Launch Angle
• Average Exit Velocity
• Max Exit Velocity
• Hard Hit Launch Angle: The average launch angle for all batted balls hit over 98 mph.
• Average Hard Hit Difference: The difference between the HHLA and the angle for the sub-98 mph hits. From yesterday’s research, hitters start to see a production decline at a 0 AHHD and it accelerates around -4.4 AHHD. Basically, the batter is trying to get too much loft and his batted balls are going for weak flyouts.

I’m plotting the best-fit curves using the LOWESS (LOcally WEighted Scatter-plot Smoother) method. The curves use the nearest data points to create a best-fit line. Additionally, I’ve weighted the curve by the monthly batted balls. These values are represented by the dot size in each graph.
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Yesterday, I introduced Hard Hit Launch Angle (HHLA) and Average Hard Hit Difference (AHHD) after reading a report from Driveline Baseball. After working my way through much of the boring but necessary background information, I’m now going to dive into some players to help explain some of their changes in production. In several cases, nothing was obvious with previous stats, but the two new measures helped a ton to explain some changes. Here is an examination of four hitters who broke out or busted last season.

For the analysis, I’m debuting new comparison graphs. They are monthly StatCast data is plotted against:

• Average Launch Angle
• Average Exit Velocity
• Max Exit Velocity
• Hard Hit Launch Angle: The average launch angle for all batted balls hit over 98 mph.
• Average Hard Hit Difference: The difference between the HHLA and the angle for the sub-98 mph hits. From yesterday’s research, hitters start to see a production decline at a 0 AHHD and it accelerates around -4.4 AHHD. Basically, the batter is trying to get too much loft and his batted balls are going for weak flyouts.

I’m plotting the best-fit curves using the LOWESS (LOcally WEighted Scatter-plot Smoother) method. The curves use the nearest data points to create a best-fit line. Additionally, I’ve weighted the curve by the monthly batted balls. These values are represented by the dot size in each graph.

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I had no idea who Dylan Moser was. In all respects to Dylan and his family, I still don’t. When I saw an article about him come through my feed, I was interested in how Tanner Stokey described Driveline Baseball’s evaluation of Moser. While Driveline has its own advocates and critics, it pushes the research bounds so I wanted to see what they considered important about Mr. Moser. Immediately, I saw this little nugget.

The “Average Hit Angle of Hard Hit Balls” caught my eye and I’ve been investigating its implications ever since.

Determining and finding the effectiveness of a hitter’s launch angle spread has been investigated several times in the past. Andrew Perpetua pointed out the importance of High Line Drives (a close cousin to Barrels) and how too much of an uppercut can hurt a player’s production. Alex Chamberlain and Brock Hammit both found a link between the standard deviation in launch angle and increased production.
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With the season delayed, I’ve had time to dive into some shelved projects including creating some unique projections. Today, I’m going to introduce my StatCast hitter projections.

I created the projections with inspiration from “The Model Thinker” by Scott Page.* The author states, “do not put too much faith in one model”. To further explain this stance, he states:

“The lesson should be clear: if we can construct multiple diverse, accurate models, then we can make very acurate predictions and valuations and choose good actions.

…

Keep in mind, these second and third models need not be better than the first model. They could be worse. If they are a little less accurate, but categorically (in the literal sense) different, they should be added to the mix. “

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In rounding out my series on the most important factors influencing components of BABIP, I will be looking into what most affects a hitter’s batting average on ground balls. So far, the results of these analyses have been consistent. Launch angle has been the main driver of BABIP for pitchers, and it has been for hitters as well, at least when they are launching flyballs. The story is a different one, though, when hitters put the ball on the ground. Ground ball launch angle was not a significant factor in determining a hitter’s ground ball batting average, and neither was ground ball exit velocity.

Whether or not a hitter pulls grounders has much to say about whether that player will hit for average on grounders. There is a negative relationship between these variables that is significant at p < .0001 and with a Pearson’s r of .27. Even more important is how fast the hitter is. The Pearson’s r for the positive correlation between average sprint speed and ground ball batting average was .45.
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In a pair of recent columns, I looked into what factors have impacted flyball BABIP (or FB BABIP) and ground ball batting average for pitchers, and those analyses were linked by a common finding. Whether pitchers are allowing balls that are in play in the air or on the ground, the launch angles of those batted balls go a long way towards explaining whether they become base hits. Now I am turning my attention to flyball BABIP for hitters, and the trend continues. While flyball pull rate, average flyball distance and average exit velocity, both on flyballs and line drives combined and on flyballs alone, did not have significant relationships with FB BABIP for hitters, average flyball launch angle (FB LA) turned out to be a statistically significant factor yet again (p < .0006, r = .19)
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In the second installment in my series on the factors impacting components of BABIP, I move on from flyball BABIP for pitchers to ground ball batting average for pitchers. This analysis produced one result that really surprised me: whether or not a pitcher has a tendency to allowed pulled grounders does not have much of an impact on the ground ball batting average they allow. I didn’t anticipate this, because hitters put up a collective .180 batting average on pulled grounders in 2019, but a .306 average on all other grounders. For pitchers who allowed at least 225 grounders in seasons between 2015 and 2019 (n=286), the negative relationship between pull rate and ground ball batting average allowed (GB Avg) was significant at p < .05, but with just an .012 Pearson’s r.
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A little more than a year ago, Al Melchior had the brilliant and beautifully straightforward idea of investigating how strongly pretty much ever Statcast metric correlated with various traditional power metrics and compiling them in one post. He asked me to help out, which I was more than glad to do.

Recently, I saw folks talking about this again, and someone asked specifically about the 2019 season. I figured I could refresh the values from the original post quickly enough (certainly a lot more quickly than I did last time), and it would also help bring pertinent information to the fore for folks neck-deep in draft prep.

Spoiler alert: the results barely changed. But! I do feel more confident in this particular set of values, as I nerded out with programming instead of pulling dozens of different queries from the Baseball Savant search function and constantly getting frazzled.

OK, here’s the goods. For 2019 hitters:

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Expected weighted on-base average (xwOBA) is one of Statcast’s most important additions to the Sabermetric sphere. It’s a simple premise — estimate a hitter’s deserved production based, simply, on his combinations of exit velocity (EV) and launch angle (LA) — with robust implications and applications. It’s remarkable how powerful the metric is with just two inputs.

However, the metric is not without its faults (or complaints from those who use it). Its simplicity is beautiful but inherently and knowingly lacking, accounting minimally or not at all for:

1. spray (lateral) angle (touched upon here),
2. a player’s foot speed (discussed more thoroughly here),
3. park factors, and
4. opposing defense.

None of this necessarily serves as an indictment of xwOBA. The number of inputs you include affects the purpose you want it to serve. That is, do you want it to be descriptive or predictive? How about both? Maybe defense shouldn’t be included, then, if we can’t reasonably expect a hitter to face the same caliber of defense each year, something that is out of his control.

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New year, new deserved barrels metric. In October, I took a crack at devising a “deserved barrels” metric in which I took the basic components of a barrel — a hitter’s exit velocity (EV) and launch angle (LA) — and determined the capacity in which the components relate to Statcast’s barrel rate metric (barrels per batted ball event, or “Brls/BBE %” on Baseball Savant). I included squared terms (EV², LA²) assuming the relationship is not linear. (A launch angle that’s too steep is detrimental, for example.)

Further offseason research led me to additional insights:

• Launch angle consistency (“tightness”) is important, correlating with higher BABIPs and more repeatable EVs.
• Launch angle grade in general is important, especially for batted ball quality, not just batted ball frequency, as indicated by batting average on balls in play (BABIP).

There exist many measures of contact quality; barrel rate captures how often a hitter produces high-quality contact. (Hard-hit rate functions similarly but ignores launch angle, to my knowledge, making barrel rate arguably superior.) It only made sense, then, that the latter finding above — that launch angle tightness matters to batted ball quality — should be incorporated into my deserved barrels work somehow.

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