An introductory post on effective velocity using Lance Lynn PITCHf/x data

Last week, Joe wrote an in-depth PITCHf/x analysis of Lance Lynn's non-pitcher strikeouts in 2014, looking at factors such as pitch type, sequencing, velocity, and location. In the comments section, there were multiple requests made to take this analysis one step further and write about it in terms of effective velocity (EV). What follows is our introductory attempt to do just that.

Effective velocity is a new concept that many people, even in the sabermetric community, may be unaware of. Last year, Jason Turbow wrote an excellent feature article on SB Nation explaining the concept of effective velocity in detail. In his article, Turbow wrote:

Effective Velocity is made up of six tenets, some of which are commonsense and already utilized by successful pitchers at the game's highest levels, others so complex that even major league coaches have difficulty grasping them. It starts with the idea that all pitches are not equal — even those that appear to be identical on the radar gun.

It hinges on response time. [Perry] Husband's model is based on the arc of hitters' swings, and the understanding that bats must move farther to reach pitches on the inner part of the plate than on the outside edge. Put another way, a batter can hit an outside fastball as it crosses the plate, but to make solid contact with an inside fastball, he must reach it much sooner — up to 2 feet in front of the plate — which requires the hitter to move the bat a greater distance in less time. With this detail in mind, it makes sense to build an approach based not on a pitch's radar speed, but how quickly the man standing in the batter's box can react to it.

Effective velocity is dependent on how the batter perceives a pitch and how much time he has to react to that pitch, given its location. Pitches that are higher and/or more inside will have a higher effective velocity while pitches that are lower and/or more outside will have a lower effective velocity. According to the article referenced above, as well as this helpful summary of effective velocity, a 90 mph fastball in the strike zone can have an effective velocity range of 85-95 mph, depending on where it is located. For example, a 90 mph fastball on the low outside corner of the strike zone will have an effective velocity of 85 mph while a 90 mph fastball on the upper inside corner of the strike zone will have an effective velocity of 95 mph. This range becomes even wider with pitches outside the strike zone, as a single pitch can have an effective velocity that is 7-10 mph different from its actual velocity.

The following GIF (thank you, @mstreeter06) includes the final two pitches of Lynn striking out Ryan Braun and is a perfect visual example of the theory of effective velocity:

Set-up: 94 MPH fourseamer (MLB/FSM); 95 MPH fourseamer (BrooksBaseball)

Put-away: 94 MPH fourseamer (MLB/FSM); 95 MPH fourseamer (BrooksBaseball)

Regardless of which velocity tracking system you choose to use, Lynn's down and away set-up pitch was thrown at the same actual velocity of his up and in put-away pitch (94 or 95 MPH). Without access to pitch location (either via video on in charts on sites like BrooksBaseball), these two pitches would be seemingly identical—mid-90s fourseam fastballs. However, based on the theory of effective velocity, we are fairly certain that this is not what a hitter experiences. While the put-away pitch read at the same actual velocity on a radar gun, its up and in location tied up Braun, largely because he perceived it as being a noticeably faster pitch (aka: he had to "move [his] bat a greater distance in less time").

Well, given the abundance of PITCHf/x data widely available (thanks, BrooksBaseball), we thought we'd take a shot at converting actual velocity to effective velocity based on our (perhaps limited) understanding of the concept. We figured that working with Lynn's strikeout data would be a good starting point, since much of the data needed had already been collected for last week's article. For each strikeout, we collected data for the set-up pitch and the put-away pitch, including pitch type, location, and velocity. Location was broken down into nine quadrants with each pitch having both a vertical and a horizontal location (Vertical location: U=Up, D=Down, M=Middle; Horizontal location: O=Out, I=In, M=Middle).

To change from actual velocity to effective velocity, we made the following adjustments based on pitch location:

Given what was presented in the articles referenced above, we thought the adjustments seen in the table were reasonable estimates, as they were in the middle of the ranges given for certain locations. Obviously, these adjustments are far from perfect, as we categorized pitches into one of nine locations, with no distinction between pitches inside and outside the strike zone (just yet, at least). Unfortunately, until we have pinpoint measures of effective velocity, all we can do is make estimates in this fashion. Nevertheless, we hope these adjustments will help illustrate the concept of effective velocity and show how location, velocity, and pitch selection can be used effectively against major league hitters.

Revisiting the final two pitches of Lynn's strikeout of Braun using our velocity adjustments, we see that the effective velocity of Lynn's set-up pitch (down and away) was 90 MPH, as compared to an EV of 100 MPH on his put-away pitch (up and in). This creates a batter-perceived velocity difference of 10 MPH on two pitches with identical actual velocities. Remember, our adjustments make no distinction of whether the pitches are inside or outside of the strike zone. I bring this up because some references would have made even larger adjustments on each pitch (because neither one was actually in the strike zone) which would have subsequently led to an even larger difference between the two. This is truly fascinating considering both pitches were recorded at 94 or 95 MPH, and it puts some reasoning behind why Braun looked so calm on a "90 MPH" pitch low and way followed by being so far behind a "100 MPH" pitch up an in.

As we all already know, one of the most important parts of pitching is changing speeds to keep a hitter off balance. In particular, a wider velocity gap between two pitches will be make it difficult for a hitter to time the second pitch with the first one still fresh in his mind. Using effective velocity, a pitcher can increase the perceived velocity gap between two pitches by throwing them in certain locations. In looking at Lynn's 162 non-pitcher strikeouts from last season, it appears that Lynn used this tactic. 102 of these strikeouts had a higher EV gap than actual velocity gap, 42 of these strikeouts had the same EV gap and actual velocity gap, and only 18 of these strikeouts had a smaller EV gap than actual gap.

To be honest, today's article (already nearing 1,300+ words) merely scrapes the surface of what may or may not end up being an incredibly interesting aspect of pitching (and hitting for that matter). Nick and I have already started collecting data on Jaime Garcia and plan to check on 2013 Michael Wacha soon thereafter. While Nick and I are both extremely busy today, we will definitely be checking in on the comments to see what adjustments you propose us to make going forward.

Credit to @mstreeter06 for the GIF and BrooksBaseball for the data collected for the first post on Lynn.