“We see a lot on the telecast and now on the stadiums there broadcasting that he just hit that at 102 mph, and it seems to me that that’s an impressive number on the surface, but it doesn’t give you much… All that could mean is a hard ground ball to the shortstop if the launch angle is downward or is flat. It seems to me that the exit velocity is almost like the pitch velocity is in baseball. It might tell you what it was but not much after that,” said Ryan Sullivan on the NatsGM Show.
Since last season, a number of broadcasts have included some Statcast numbers. This, to me, is refreshing.
Why? Because broadcasts and baseball have traditionally been dogmatic in adapting to change. When a new statistic is invented, it often takes time before broadcasters start using it, and in many cases, they still don’t. Sure, one now hears about OBP and OPS, but rarely about more advanced stats. And even those took a number of years before being incorporated into broadcasts.
Maybe one of the reasons broadcasts are so open to using Statcast numbers is because the numbers are intuitive. After all, hearing that a ball came off the bat at 100 mph is much more intuitive than someone citing a player’s True Average or Weighted Runs Created Plus. People can intuitively understand that a ball was hit at 100 mph but a .345 TAv. takes some explanation.
With that said, the delivery of the information is at times problematic. For example, as Ryan stated, simply giving the exit velocity doesn’t really say a whole lot. At the end of the day, it’s just a number and numbers don’t really mean anything without context.
So let’s add context.
One way to add context to exit velocity is finding out the median or the average exit velocity. If a player is above that average then one can say that he hit the ball hard, below then he made week contact. But, that’s not very interesting and it’s already been done.
What’s more interesting is combining exit velocity with launch angle. Launch angle is “the vertical angle at which the ball leaves a player’s bat after being struck.” According to MLB.com, a launch angle less than 10 degrees results in a ground ball. An angle of 10-25 degrees is a line drive, 25-50 is a fly ball, and over 50 degrees is a pop-up.
So, for example, if a baseball is hit 100 mph but it’s got a launch angle of fewer than 10 degrees then that’s going to result in a ground ball. With a launch angle of 25, however, then that’s probably a home run.
In Rob Arthur’s article, “The New Science of Hitting,” he displayed a visual entitled “The Sweet Spot.” The sweet spot is, “The very best hitters in MLB tend to smack lots of balls with launch angles around 25 degrees and exit velocities above 90 miles per hour, corresponding to the area of the plot rich in such valuable plays as home runs and doubles.”
Basically, if you hit the ball at a certain angle off the bat and at a certain speed then good things happen most of the time. Here’s how this looks for the Brewers. The difference here is that I included all events, which are separated by color. There is a color legend, and you can isolate any specific event by using the filter option and choosing the event of your choice. You can also look for any player you want by unselecting “All” and selecting the player or players of your choice.
As you can see from the top, an angle of more than 50 degrees almost always results in a pop-up or a fly out, but naturally, not all pop-ups come from more than a 50-degree angle. Some come from a 40-degree angle and some even come from a 30-degree angle. That’s primarily due to the exit velocity. This is the same for everything. Including groundout’s, fly outs, line outs, doubles, and more. Singles, as you can see, are a bit of a mess. Some can come from groundballs with low launch angles and others can come from high launch angles, with weak or hard exit velocities. Triples also seem to be quite random. Those type of hits are probably more impacted by luck, the batter’s speed, and the stadium.
Homers are a bit of a different story. There’s a specific area where the ball has to be hit. The ball generally needs to be struck at an angle in the mid-high 20s and low 30s, usually with an exit velocity at 95+ mph, for it to be a home run.
The most interesting data point here is the big outlier home run hit by Carlos Gomez. Now, I said that typically one needs to hit the ball in the mid-to-high 20s for the ball to be a home run. This is a generalization of course; in some instances, a ball can be a home run if hit with a low 20 launch angle, or even with a launch angle in the high teens. This is unlikely but still can happen. For example, five of the Brewers home runs in 2015 had a launch angle between 18-20. The Gomez home run, however, had a launch angle of 16.34. That’s a very low launch angle for a home run. This, therefore, begs the question, how in the world did he hit that one out?
First, let’s watch the home run.
Off the bat, to me, it looked like it was going to be a double and then the ball just carried.
First, though, the ball was evidently crushed. It had an exit velocity of 110 mph. But, Khris Davis hit a ball at 110 mph with an 18 launch angle and that was a double.
Second, exit velocity and launch angle don’t tell us everything. For example, the ball was a home run in Miller Park but, perhaps, would not be in a less hitter friendly ballpark, such as Petco Park. Miller park, in 2015, was the fifth friendliest ballpark for left-handed hitters. Gomez, however, is right handed. Miller Park is less friendly to right-handed hitters, as it has a park effect of 100. Meaning it’s basically league average. It doesn’t kill them, but at the same time, it’s not Coors Field.
What this can tell us is that launch angle and exit velocity have the potential to further our understanding of park effects. We should, now, be able to get a better sense of just how favorable Coors Field and other ballparks are.
Thirdly, the home run was hit on May 29th, 2015. If you watch the gif again many people are in shorts and tank tops, meaning that the weather must have been warm. And, thanks to Alan Nathan we know that, “…an elevated temperature does indeed lead to longer fly ball distances and more home runs, exactly as everyone expects.” Six home runs were hit in that game, which is a lot.
To some extent, I would expect that all these elements played a role in Gomez’s unusual home run. Meaning, even launch angle and exit velocity don’t tell us everything, but hopefully they’ll enrich our understanding of many elements.
We’re just starting to grasp the potential of Statcast. It’s already yielded some interesting findings and should lead to more. More importantly, it should help increase the reliability and precision of stats, such as having better projection models, which people are already starting to experiment with. Rob Arthur has also championed the idea that Statcast can lead to the truth of the hot streak. We should also get a better understanding of park effects. Surely, there is more that we’ll be able to learn, especially once defensive metrics will start to trickle out. But, the early signs are promising.