Stuff

*This is part one of a three-part series introducing STUFF, a objective-based statistic using Pitch f/x and available scouting data.

by: Michael Melaragno

Bridging the gap between scouts and the use of statistical analysis is not as hard as we would believe. Since the mainstream indoctrination of Bill James and his baseball abstracts, the constant argument as to which sentiment brings forth a higher probability of an organization building a winning team always seemed needless to me. The question I would always ask is: Why not incorporate both scouts and stats?

The more thought that was given to this question, one realizes that it is just not about the why organizations do not but rather how they go about doing it. There has not been much written about the methodology behind the how, as this is usually kept as proprietary information and under tight scrutiny. The ability to objectively analyze what a scout sees in a player can have tremendous advantages in the marketplace. To the extent that a team utilizes an objective analysis could be the difference between an organization going in the right direction and one going in the wrong direction.

So often we read or hear about a pitchers “stuff.” Also known as his “repertoire” or “tools of the trade,” it is what defines the pitcher. His “stuff” consists of what type of pitch he throws, how and when he throws it, and how good the pitch is compared to his peers.  Every pitcher has the same goal in mind- to keep the batter off the base paths and record the out. However, not every pitcher does this the same way. Scouts, fans and front office personnel grade pitchers based on the different ways in which they record outs. Some pitchers over-power hitters while others use finesse; some have two pitches while others have five. It all depends on what role the organization puts the pitcher in. While we grade these pitchers based solely on subjective analysis, I will propose a method to which we can incorporate relatively new technology and old fashioned scouting methods to come up with a quantitative analysis that would make even Billy Bean proud. But before we get into the dirty little details, I must provide a little primer on PITCH f/x, the data system to which I will use to describe my system, along with the various pitches that are thrown at the Major League level.

PITCHf/x is a system developed by Sportvision and introduced in Major League Baseball during the 2006 playoffs. It uses two cameras to record the position of the pitched baseball during its flight from the pitcher’s hand to home plate, and various parameters are measured and calculated to describe the trajectory and speed of each pitch. It was instituted in most ballparks throughout MLB as the 2007 season progressed, such that we have PITCHf/x data for a little over a third of the games from 2007. MLBAM used the PITCHf/x data in their Enhanced Gameday application and also made the data freely available for downloading and research.

In some ways, PITCHf/x is a bridge between scouting and analysis, giving us an objective window into the batter-pitcher matchup at a level we’ve never seen before. In 2008, the system should be installed in every major-league ballpark, and we will hopefully have complete detail for every pitch, although MLB has not committed to whether all the data will continue to be freely available in the future.

The system enables to graphically Some people are good at identifying pitch types while at the ballpark or from the center field TV camera view. That was a splitter. That was a sinker. That was a slider. Etc. I am one of those people. If you are not one of those people either, PITCHf/x was made for you. Even if you are one of those people, PITCHf/x can be a useful resource for learning about how different pitches move.

A pitcher’s fastest pitch is usually a four-seam fastball. A typical major-league fastball is around 90 mph, many a little faster, some a little slower. The fastball from a right-handed pitcher breaks in toward a right-handed hitter. Pitches from a lefty move the opposite way; a fastball from a lefty breaks away from a right-handed hitter. I’ll describe the movement for pitches from a righty and you can flip the orientation if you want to know how a similar pitch from a lefty would behave.

Pitchers throw variations of the fastball by changing the grip on the baseball or parts of their motion and delivery. The most popular variation is a two-seam fastball, which often thrown a couple mph slower and breaks in more and drops more to a right-handed hitter from a right-handed pitcher than the four-seamer. The cut fastball is also thrown a few mph slower than the four-seamer and breaks away a little from a right-handed hitter, if it breaks at all.

The most popular off-speed pitch is the changeup, which is typically thrown 7-10 mph slower than a pitcher’s fastball. It usually has a similar break to the fastball, in toward a right-handed hitter. Some pitchers employ a grip on their changeup to impart additional movement, usually causing the pitch to break in more and drop more to a right-handed hitter. The split-finger fastball acts much like a changeup except that its velocity and movement are usually somewhere between the fastball and changeup.

Breaking balls include the slider and curveball. The slider is usually thrown at the same speed as the changeup or sometimes a few mph faster. The movement on the slider can vary quite a bit from one pitcher to another. Some sliders move like a cutter, with hardly any left-right break. Other sliders move more like a curveball, which breaks away from a right-handed hitter and down. The curveball is the slowest pitch, thrown in the 65-80 mph range in major league baseball.

The knuckleball is a special case in major league baseball these days. As far as I know, there were only two regular practitioners of the pitch in the majors last year: Tim Wakefield and Charlie Haeger. The pitch is thrown with very little spin such that the airstream interaction with the seam orientation causes the baseball to move unpredictably. Wakefield and Haeger throw the knuckleball about 65-70 mph.

Of course, there are a number of variations and combinations of the above pitches and specialty pitches like the screwball and gyroball and even the 50-mph Orlando Hernandez eephus pitch.

Below is a simple diagram graphically showing what each pitch looks like using Pitch f/x system, view from the catcher:

PITCHf/x analysis and research is a promising field with wide application and broad interest, and there are a number of people who have made important contributions ever since the system application. As a result, there are many different formats for presenting the results. I’ll summarize and explain a few of them here and give a more detailed explanation of some of the graphs that I will use for my new stat.

The most common plots presented by other PITCHf/x researchers include information about the speed and spin-induced deflection of pitches. To the best of my knowledge, Joe Sheehan was the first to produce these plots, showing speed on the vertical axis and the two components of spin deflection as two sets of points on the horizontal axis. Joe hasn’t done much pitch classification work recently, but he deserves a nod as the groundbreaker in that field.

Something you’re more likely to encounter these days is a plot from John Walsh, who wrote for various sabermetric websites. He plots vertical “movement” versus horizontal “movement”, where movement refers to the spin-induced deflection, and indicates speed by color-coding the points on the graph.

Most common of all are the plots from Josh Kalk’s pitcher cards, particularly the plots of vertical “break” versus horizontal “break”. These are similar to John Walsh’s plots except that instead of color-coding for speed, the points on the graph are color-coded by pitch type. Josh has separate graphs that plot speed versus horizontal break and speed versus vertical break, reminiscent of the original Sheehan plots. Josh’s player cards also contain information on release point, which is the height and left-right position of the pitch measured 50 feet from home plate, which is soon after the actual release by the pitcher.

In the past I have presented graphs similar to those of Sheehan and Kalk, but more recently I’ve adopted a graph from Alan Nathan as my mainstay. It is a polar plot, with the speed of the pitch on the radial axis. The faster the pitch, the farther from the center. The slower the pitch, the closer to the center. The angle is the angle of the Magnus force, which is the force that cause the ball to break. Curveballs break down, so they’ll be in the bottom part of the graph. Sliders break away from a right-handed hitter, so they’ll be on the left side of the graph. The Magnus force of a fastball pushes the ball up, causing it to drop less than it normally would due to gravity alone, so the fastballs will be on the top part of the graph.

There is also a graph of what I call “late break”, which is a combination of the effects of spin deflection and gravity as well as the speed of the pitch. The goal is to show something close to what the hitter perceives as the break or movement of the pitch. I calculate the deflection of the pitch due to two forces, spin and gravity, in the last 0.25 seconds of its trajectory before it crosses the plate, an idea I got from Tom Tango. I chose a quarter second because that’s roughly the reaction time of a batter executing a swing. I chose to include the effect of gravity because I believe that more accurately reflects what hitters see. Hitters don’t attempt to hit a gravity-less pitch; they attempt to hit a pitch that’s being affected by gravity and being deflected by spin.

In part two of our series, I will incorporate Pitch f/x data and scouting analysis together. Hold on, it shall be fun.