Baseball Prospectus News

10-Year Projections, UPSIDE, Percentiles, and Comparables

by Rob McQuown

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Baseball Prospectus is pleased to announce five new additions to the 2014 player cards, three which have been missing for a few years.

10-Year Forecast: A projection of player performance over the next decade.
UPSIDE: Not all players with the same projection have the same potential for greatness. UPSIDE gives us a way to distinguish between them.
Comparable Players: The "heart" of PECOTA. The player cards display each player's 100 closest comparables.
Percentile Forecast: The 10th- through 90th-percentile projections for each player, encompassing the full range of projected performance from worst case to best case.
Diagnostics: As also seen on the PECOTA weighted-means spreadsheet, each player's Breakout Rate, Improvement Rate, Collapse Rate, MLB%, and Attrition Rate, based on the weighted similarities of his most-comparable players.

The original intended use for UPSIDE and long-term projections was to aid in discerning how various prospects might do during the time when their organization had control over them (or roughly five full-time seasons). And the methodology was based on using actual performance of the most-comparable players over the years in question. There have been some changes to the details over the years, but the core concept has been brought back for 2014, with projections through 2023. Here are some clarifications of what we're doing now:

Our current definition of PEAK is the one set forth in the Glossary. PEAK doesn't refer to a particular statistic; it refers to a sum total of any given statistic over a contiguous set of five seasons. These five seasons will be the next five for player ages 24 or higher. But for player younger than 24, they will be the most productive five-year window up through and including the age-28 season. For example, either the age 23-27 or age 24-28 span will be used for a for a 23-year-old player, whichever represents the highest sum total of the statistic being measured. Continuing the example, such a player could have a "PEAK FRAA" that is the sum of his FRAA values from his age-23 through age-27 seasons and could also have a "PEAK WARP" that is the sum of his WARP values from his age-24 through age-28 seasons.

UPSIDE is now a composite of the PEAK values of non-negative WARP for the top 20 most-comparable players (weighted by similarity). As Nate Silver observed in 2006:

UPSIDE...is focused only the possibility that the player develops into an above average major leaguer. It doesn’t care whether a player winds up riding the major league bench, gets stuck in Double-A, becomes the new Luis Rivas, or goes off to Australia to smoke ganja with Ricky Williams. Each of these outcomes is equally undesirable, and UPSIDE recognizes that.

We'll be using UPSIDE to compare PECOTA's top prospects to those of the BP Prospect Staff in an upcoming article series, so stay tuned for that.

The top 20 most-comparable players are the same ones used for the 2014 PECOTA projections and can include both major-league and minor-league seasons, though players are considered much more comparable to players at similar classifications.

Now for the fun stuff. To get to the new features without scrolling all the way down the player card, simply click on the "More PECOTA" tab located near the middle of the navigation bar:

From there, all the new features follow one after another:

The "PEAK 5" UPSIDE value for Sogard is the sum of his first five UPSIDE scores, as he's beyond the age where the system considers other options.

Last but not least are the most-comparable players based on similarity score. "The comparables," as Colin Wyers put it, "represent a lot of tedious number crunching (measuring Euclidean distance in n-th dimensional space, if you want to be precise)." The "Similarity Index" is based on the Similarity Scores of the top 100 most-comparable players. And the Similarity Scores are based on the Euclidean distances between the player in question (in this case, Sogard in 2014, which will be his age-28 season) and every other player in our database at the same age (for example, Jeff Keppinger in 2008—his age-28 season).

The "Trend" column can be a bit confusing—it's a simple up/down/neutral metric based on whether the comparable player over- or under-performed his baseline projection by 20 percent. For the "baseline" projection, only a generic aging curve is used for comparisons—the system doesn't evaluate the player's projection based on his comparables. Protip: Note the easily-overlooked arrow on the bottom right, which allows for the selection of comparable players 11-100.

We hope you enjoy these PECOTA-related offerings. If you have questions about methodology or navigation, please post them in the comments below or email customer service.

Rob McQuown is an author of Baseball Prospectus. Follow @robmcquown
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