Where We Left Off

In Part I of my study of fastball velocity’s DFS implications, I questioned whether sudden drops or jumps in average velocity should be weighed the same across the board. I presented a few other variables that likely need to be considered, such as how heavily the pitcher relies on velocity alone and at what point during the season the change occurs.

Now, we are going to go even further down the rabbit hole, this time splitting up pitchers into groups based on their batted-ball profiles and most frequently thrown pitches. As I cautioned in Part I, since this type of advanced data has only recently become available, we are dealing with rather small sample sizes in most cases. I think it would be a mistake to form any concrete conclusions based on the data here, but that doesn’t mean it’s not still valuable to analyze the data we do have.

Now that we’re all caught up, let’s dive right into Part II.

By Batted-Ball Profile

In Part I, we separated pitchers into groups based on their Average Fastball Velocity. That is a good place to start, but certainly not the whole story. In this section, we will look at pitcher batted-ball profiles – do they pitch to contact, do guys hit a lot of flyballs on them, do they have control problems, etc.?

Groundball Pitchers

We’ll start with guys who pitch to contact, hoping to induce weak contact and force groundball outs. Here are the players that make up this group:

 

Overall, the results haven’t been bad and our baseline Plus/Minus is going to be +0.58.

 

Let’s look at how these pitchers did when they added at least 1.0 MPH to their recent velocity:

 

Pretty surprising. Remember though, these are the pitchers who rely on groundball outs. They aren’t necessarily trying to blow a high-90’s fastball by batters (though some in the group do have high average velocities). I won’t pretend to be an expert on pitching mechanics, but it seems reasonable that a pitcher could create groundball outs at both high and low velocities.

As time goes on, my guess is that this Plus/Minus is going to come up a bit. To me, it doesn’t make sense that extra velocity is a “bad” thing, but maybe it’s not as helpful here as it would be other places.

Flyball Pitchers

Moving on, we’ll look at flyball pitchers next. I think there can be a misconception that “flyball” equals “bad” for pitchers, but that is not necessarily the case. As we’ll see below, there are several big names among qualifiers, including Max Scherzer and Danny Salazar. You can allow flyballs; you just need to make sure the ballpark is going to hold those flyballs from becoming home runs. That’s likely a big reason why, if you look at someone like Jake Odorizzi, there is a pretty noticeable home/away split.

 

We have a nice and easy baseline Plus/Minus for this group: Zero.

 

Before applying the velocity filters, my assumption was that pitchers in this group may not do as well with increased velocity as in other groups. A faster pitch can lead to harder contact, and harder contact on a flyball is very bad (for pitchers).

So far at least, my assumption is wrong:

 

The pitchers with the most matches in this cohort were Trevor Bauer, Max Scherzer, Hector Santiago, and Matt Shoemaker. Santiago started out the 2016 season playing very well, racking up 27 strikeouts over his first four starts, which is a pretty high number for him. During that same period of time, his velocity was up. Rather than seeing that higher velocity lead to more home runs – he did allow four, but that’s about what we would expect from him over a four-game sample – it led to more strikeouts.

Further, the Consistency rating of 57.4 is among the highest we have seen so far. Flyball pitchers are more prone to blowup games than other pitcher types because their mistakes lead to home runs more frequently. So even given the group’s inherent inconsistency, they are relatively consistent when velocity is up (so far).

On the other hand, when velocity is down among this group, the results have been horrible:

 

While my assumption was that a higher velocity would lead to harder contact (which would be especially bad for flyball pitchers), it looks like the opposite is true. A lower velocity likely makes the pitches more hittable, which is especially bad for flyball pitchers. I’ll keep mentioning the small samples that we are working with, but when there is nearly a five-point swing per-player, per-game, it’s pretty hard to ignore.

By Pitch Type

I’ll make this section shorter than the preceding ones, but I quickly wanted to run through velocity change by pitch type. Here, pitchers are broken down into groups based on how often they throw each pitch. On FanGraphs, I sorted by how frequently each pitch was thrown and compiled a list of the top-25 to 30 pitchers in each case.

Note that our velocity filters measure fastball velocity. So while we aren’t measuring velocity change on these specific pitches, A) velocity will be down across the board in most cases, and B) pitches work in concert with each other; the fastball sets up the changeup, and so on. Even if a pitcher’s fastball is the only pitch affected, it will still have an indirect effect on the target pitch.

 

The “Changeup” group was interesting because several of the matches feature a mid-90’s fastball (Chris Sale, Carlos Carrasco, and David Price). But the results also included Jered Weaver and his notoriously slow fastball. The results are not as clear in this case and we’re going to have to hold out for more data before making any conclusions.

 

Interestingly, we see the same oddity with pitchers who lean on their curveball – when fastball velocity is up, their overall Plus/Minus remains slightly down. Over the same number of results, a decrease in velocity had a greater negative effect on pitchers who throw a high percentage of curveballs.

That trend more or less holds true for the next two groups, which consist of pitchers who threw the most sinkers and sliders:

 

For pitchers who threw a lower percentage of fastballs than average, a decrease in fastball velocity still hurt. Interestingly though, an increase in velocity was not very helpful. In only one of the groups was the Plus/Minus above zero – the group who threw the most sliders – and even then, the Plus/Minus was only +0.60.

I think this is actionable because most DFS players – the ones who are watching velocity anyway – are probably going to uniformly upgrade pitchers whose velocity is up across the board. Although individually the sample sizes of the groups were small, taken as a whole, we can see that in 230 or so combined starts that has not been an approach that yields positive results for pitchers who don’t rely primarily on their fastball.

The final (and most important) group to look at is the pitchers who throw the highest percentage of fastballs. You would expect a change in fastball velocity to correlate highly with performance in this group:

 

And you would be somewhat correct. A decrease in velocity of 1.0 MPH or more led to devastating results, while an increased velocity only matched the baseline Plus/Minus; it did not exceed it.

Final Thoughts

I spent much of this article reiterating the fact that we are working with small samples and shouldn’t draw any hard conclusions based on the data. That is true, but I think there are still several things we can take away from the study:

• In nearly every case, a decrease in recent Average Fastball Velocity of 1.0 or more miles per hour led to very negative results.

• When recent velocity increased, the results were a little muddier. In some groups – for example, low velocity pitchers and flyball pitchers – adding velocity was very beneficial. In other groups that you would expect to be heavily influenced by fastball velocity, such as those who throw fastballs most frequently and those with the highest overall average velocity, it didn’t seem to matter as much. Plus/Minus in games where velocity was up failed to exceed the baseline Plus/Minus in each case.

• An early-season velocity drop is probably less concerning than one in the summer. Though I think it is sometimes overused and misapplied, I do think there is truth to the idea that sometimes guys naturally add more velocity as the summer approaches (see: Aaron Sanchez). Also, other pitchers change their repertoire over the offseason and a lower reliance on a high-velocity fastball is by design (see: Stephen Strasburg and Michael Wacha).

Finally, when you’ve identified that a pitcher’s recent Average Fastball Velocity is down a significant amount, you’ve found data that can be very important and very actionable in MLB DFS. But as important as that information is, understanding why the velocity is down is just as important, if not more so.