WAR, FIP, WPA: A look at some of baseball’s fancy stats

SAN FRANCISCO (AP) The days of batting average, RBIs, wins and ERA telling the whole story ended a while ago. To get the true picture of how baseball players are performing or will perform in the future takes navigating through an alphabet soup of new-age stats and acronyms.

Some of these statistics look back at what players did. Others are tools to predict future performance, allowing both real general managers and fantasy players a chance to identify under- or overvalued players.

Here’s a look at some of them, what they measure and why they’re important:

WAR: Wins Above Replacement. A single number that tries to encapsulate everything a player does as a hitter, pitcher, fielder and base runner. This allows for comparisons between a slugging first baseman and a slick-fielding shortstop; or five-tool outfielder and elite starting pitcher. The result is how many wins a specific player provided in comparison to a readily available replacement – or a so-called four-A player. Different sites have slightly different calculations but an average starter is worth about two wins, a star around four and an MVP candidate in excess of six.

FIP: Fielding Independent Pitching. Tries to measure the aspects of pitching most in control of the pitcher: walks, strikeouts, hit batsmen and home runs. The stat tries to ignore the impact of fielding and luck and is considered a better predictor of future performance than ERA. Players whose FIP is lower than their ERA are often due for rebound seasons, while those with a higher FIP than ERA might be in for regression. The average FIP is the same as the average ERA, to make for simpler comparisons. There is also a cousin of FIP, called xFIP, which measures fly balls instead of homers and assumes a pitcher gives up home runs on a league average amount of fly balls.

WPA. Win Probability Added. A different measure of wins based on the context of when events happen. It takes a team’s chance of winning a game before and after each plate appearance, with each team starting with a 50 percent chance. The hitter and pitcher each get credit or blame for any change. A homer leading off the game is worth more than one in the eighth inning of a 10-1 game but much less than one in the bottom of the ninth of a 1-1 game. WPA does not measure defense and because it depends on when players get their chances, it is not as predictive of future performance a statistics like WAR or FIP.

BABIP: Batting average on balls in play. With growing evidence that pitchers and hitters have little control over what happens once a ball is put into play, BABIP tries to eliminate the effects of luck and fielding on performance. BABIP is a form of batting average that eliminates home runs and strikeouts, while adding sacrifice flies and bunts. Players with a BABIP much below .300 are likely due for an improvement, while those much higher than .300 can be expected to regress.

BACON: Batting average on contact. Similar to BABIP, BACON also counts home runs as part of the measurement, only excluding strikeouts from the calculation.

Adjusted OPS+: Adjusted on-base plus slugging percentage. Adding on-base and slugging percentage has become an easy tool to better measure the best hitters rather than traditional stats like batting average and RBIs. Adjusted OPS+ also alters the percentage based on how the league as a whole is hitting and a player’s home ballpark. This allows for easier comparisons between eras, as well as between hitters who play at hitter-friendly Coors Field compared to cavernous Petco Park.

ERA+: Like Adjusted OPS+, ERA+ accounts for how a pitcher performs compared to the league as a whole and factors in home ballpark, once again making comparisons more accurate.

UZR: Ultimate Zone Rating. Splits the field into 64 zones and compares how well a given fielder turns balls hit into each zone into outs, compared to the league average.

ISO: Isolated Power. Measures extra bases per at-bat, or essentially slugging percentage minus batting average. Shows which players have the most power by taking singles out of slugging percentage.

Pitch f/x: A pitch-tracking system created by Sportvision and used in every stadium that tracks the speed, location and trajectory of every pitch. Sportvision also uses Hit f/x to measure what happens to batted balls and Field f/x to measure how much ground players cover and how difficult plays are in the field.