Creating a tool that considers the speed and movement of every pitch, the similarity measure allows the direct comparison of pitchers across various contexts.
The PITCHf/x optical video and TrackMan Doppler radar sensors estimate parameters of pitches, including the speed, horizontal movement and vertical movement. The data recorded by these systems can be used to develop pitcher similarity measures. These measures are valuable not only for comparing major-league pitchers to each other, but also for allowing the direct comparison of pitchers in other leagues (minor, amateur and foreign) to their MLB counterparts.
A pitcher similarity measure can be employed for multiple purposes by analysts. The identification of groups of similar pitchers can be used to generate optimized projection models , or to generate larger samples for predicting the outcome of batter/pitcher matchups , . In addition, a similarity measure allows for individual pitchers to be monitored over time in order to detect possible changes in pitch characteristics, health and throwing mechanics.
Previous methods for quantifying pitcher similarity have been limited to the comparison of pitches of the same type, which makes these methods highly dependent on the outcome of pitch-classification algorithms. Kalk ,  developed a similarity measure that compared pitches of the same type using variables that included pitch frequency, speed and movement. Loftus , ,  improved on Kalk's approach by separating pitchers by handedness while using the Kolmogorov-Smirnov distance to compare distributions. Like Kalk's method, however, this approach only considers comparisons between pitches of the same type.
A difficulty for these methods is that different pitch types for a single pitcher or across multiple pitchers can have similar properties. This causes the pitch-frequency statistics used by similarity algorithms to depend heavily on the classification process; it also prevents the comparison of similar pitches that are classified as different pitch types.
In 2016, for example, Ubaldo Jimenez's sinker averaged 91.12 mph, -7.35 inches of horizontal movement and 8.53 inches of vertical movement, while Jeremy Hellickson's four-seam fastball had nearly identical averages of 90.81 mph, -7.63 inches of horizontal movement and 8.44 inches of vertical movement. Due to this issue, Loftus  conceded that his own method is best suited for comparing individual pitches as opposed to comparing pitchers based on their entire arsenal. Gennaro  has proposed a more qualitative approach to measuring pitcher similarity by using a hand-selected set of features and weightings. The features used by this method include a pitcher's two most-common pitch types and his most-common two-pitch sequence.
In this work, we develop a pitcher similarity measure that considers the speed and movement of every pitch. We note that other factors that are less indicative of a pitcher's raw stuff such as pitch location , sequencing , and deception  also play a role in determining performance.
Does a recently high batting average bode well for Arcia's immediate fantasy future?
Orlando Arcia made his major-league debut in 2016. Initially, his fantasy value was thought to be limited because his defense was his most valuable asset. Over the course of those 55 games, Arcia hit .219/.273/.358 with four home runs, 21 runs scored, 17 RBIs and eight stolen bases. His fantasy stock wasn’t high coming into 2017. Arcia did rate as a two-star player in Mike Gianella’s initial shortstop rankings, but Mike admitted this was “a speculative pick based on stats from a year ago.”
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He's running with an opportunity to play—but how long can Taylor keep up this kind of production?
Michael Taylor entered the season with limited fantasy value. The addition of Adam Eaton made Taylor the odd-man out in Washington’s outfield. However, injuries to several players (Eaton and Jayson Werth) have made playing time available. The 26-year-old is running with the opportunity, and he started to draw serious interest from fantasy owners.
Taylor saw the biggest change in ownership rate at CBS (19 percent to 48 percent) over the past week. Similarly, he saw the largest increase at ESPN (4.5 percent to 39.3 percent). In Yahoo’s latest “Transaction Trends,” Taylor was a top-10 addition in the outfield. He’s currently a top-50 outfielder by ESPN’s player rater, and he’s been providing owners with positive values in every standard fantasy category.
A top prospect, Zimmer has a power-speed combo that has become increasingly rare in fantasy, and because of Cleveland's injury troubles in the outfield, is getting a chance to contribute now. What can we expect?
The Situation: The Indians outfield is in dire need of help due to the injuries to Abraham Almonte, Brandon Guyer and Austin Jackson. Also, while Michael Brantley has hit fairly well so far, his playing time is being managed cautiously given his recent injury history. They have addressed this situation by calling up Zimmer, one of their top prospects (No. 3 in our 2017 Indians organizational ranking).
Background: Cleveland selected Zimmer 21st overall in the 2014 amateur draft, and the start of his first full pro season could not have gone much better. After he slashed .308/.403/.493, hit 10 homers, and stole 32 bases in 335 plate appearances for High-A Lynchburg, he was named to the Carolina League All-Star team and participated in the Futures Game. However, he struggled with Double-A Akron in the second half of the season, in large part because he tried to play with a hairline fracture in his right foot. The 24-year-old’s stock fell in 2016 after striking out 115 times in just 407 plate appearances with Akron, and 56 times in 150 plate appearances for Triple-A Columbus. Zimmer got off to a better start with Columbus before his promotion, as he slashed .294/.371/.532, along with five homers, nine stolen bases, and “only” 43 strikeouts through 144 plate appearances.
Should pitchers be going up the ladder on low-power hitters or is that a danger zone?
The game of baseball moves like ivy, spreading upwards and outwards toward opportunity, consistent and chaotic. There are times in this growth where it tangles with itself, spins into contradictions. For years it drove managers to madness when their pitchers walked batters, and yet the batters themselves were encouraged by the same coaches to put the ball in play, show enough courage to take the bat off the shoulder. That seeming inequality grew as a consequence of a different priority, the valor of the productive out, available to the hitter and not his opponent.
As the culture of the game slowly grew to accept the walk and its benefits, another bias lingered: the idea that ground balls were beneficial to pitchers, while opposing hitters were often taught to swing downward on the ball and achieve that exact same result. The same cultural preference, of the ball in play (especially that vaunted achievement, the grounder to the right side with the runner on second), also promoted this strangely inconsistent set of philosophies. But batted-ball data and research has proven the benefits of not only swinging for line drives, but even putting the ball in the air compared to the grounder so long thought superior.
Bill James popularized sabermetrics. Hell, he coined the term. Several of his measures, like runs created, are still in popular use today, and his work has formed the basis for many sabermetric advances. But James created other measures that combine whimsy with measurement.
One is the power/speed number. It attempts to identify players who excel at both. It’s a simple formula: 2 x (HR x SB) / (SB +HR). That’s not #gorymath; it’s not even #goryalgebra, even if you add that it represents the harmonic mean of home runs and stolen bases.
Is it time to bring back the Herb Washington-style dedicated pinch-sprinter?
We all have radical ideas that we’d like to see implemented: the all-reliever pitching staff, the perfectly optimized lineup, the corner outfielders swapping based on batter handedness, etc. Until somebody puts them into play, they’re just ideas. What Charlie Finley did, then, was a favor to us all: He took one of those ideas and put it in play. And when it failed, we got to move on. We never had to talk about it again. For once, a crazy idea tried, tested, and settled.
Part two of a several-part series on the top tools in the minors.
Scouts spend countless hours watching and evaluating players, carefully considering the appropriate grade for each tool or each pitch a player offers. Throughout the course of the season and particularly throughout the course of ranking season, grades are tossed around with near reckless abandon. This player has plus power, and that player has a below-average fastball. This player offers above-average hit projection while that player buries hitters with a potential plus-plus curveball. It's easy to talk about the quality of an individual tool, but what does it all mean in the context of other players?
In the second edition of the annual Top Tools Series, the Baseball Prospectus Prospect Staff debated long and hard over how individual players’ tools stack up against those of their counterparts. Drawing upon our own eyewitness accounts and opinions from scouts across the league, the team debated and compiled the following ratings. The end result is a product that captures the oft-missing context of how individual player tools compare and who has the best of each tool in baseball.