Below are some definitions for some statistics that I will refer to over the next couple of posts (and most future posts).  I’m going to assume that everyone is familiar with more traditional statistics such as OBP, SLG, ERA, etc, but not necessarily familiar with some of the newer sabermetric statistics that both of my grandfathers would probably hate (my Dad may even hate them as well…I’ll ask him and provide an update at a future time).  All of these definitions are taken directly from Fangraphs, and if you would like to investigate them further, head over to the Fangraphs library page for more detailed explanations, as well as how these statistics are calculated.

BABIP (Batting Average in Balls in Play)Batting Average on Balls in Play measures how many of a batter’s balls in play go for hits.  Typically around 30% of all balls in play fall for hits.  There are three main variables that can affect BABIP rates for individual players: Defense, Luck, and Changes in Talent Level.

wOBA (weighted On Base Average) – Weighted On-Base Average combines all the different aspects of hitting into one metric, weighting each of them in proportion to their actual run value. While batting average, on-base percentage, and slugging percentage fall short in accuracy and scope, wOBA measures and captures offensive value more accurately and comprehensively.  It is set to the same scale as OBP, so league-average wOBA in a given year should be very close to the league-average OBP.

UBR (Ultimate Base Running) – Ultimate Base Running is FanGraph’s way of accounting for the value a player adds to their team via base running. This value is determined using linear weights, with each individual base running event receiving a specific run value.

WAR (Wins Above Replacement) – Wins Above Replacement is an attempt by the sabermetric baseball community to summarize a player’s total contributions to their team in one statistic.  WAR basically looks at a player and asks the question, “If this player got injured and their team had to replace them with a minor leaguer or someone from their bench, how much value would the team be losing?” This value is expressed in a wins format, so we could say that Player X is worth +6.3 wins to their team while Player Y is only worth +3.5 wins.

FIP (Fielding Independent Pitching)Fielding Independent Pitching measures what a player’s ERA should have looked like over a given time period, assuming that performance on balls in play and timing were league average.  FIP’s concept is based on the idea that pitchers have little control over balls hit in play.  A better way to assess a pitcher’s talent level is by looking at results a pitcher can control: strikeouts, walks, hit by pitches, and homeruns.  It is set to the same scale as ERA, so a league average FIP in a given year should be the same as the league average ERA.

UZR (Ultimate Zone Rating) – Ultimate Zone Rating puts a run value to defense, attempting to quantify how many runs a player saved or gave up through their fielding prowess (or lack thereof).  Components that make up UZR include outfield arm strength, infielder ability to turn the double play, the range of the fielder, and errors committed.  UZR/150 is UZR, scaled to 150 games.  As with any advanced defensive statistic, UZR contains a lot of uncertainty, especially in small sample sizes.

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