Glossary

Offense

BABIP - Batting Average on Balls In Play

HR/FB - Home Run Rate

ISO - Isolated Power

OBP - On Base Percentage

OPS - On Base Plus Slugging

Spd - Speed Score

wOBA - Weighted On Base Average

Defense

DRS - Defensive Runs Saved

UZR - Ultimate Zone Rating

Pitching 

BABIP - Batting Average on Balls In Play

BB/9 - Walk Rate

ERA - Earned Run Average

FIP - Fielding Independent Pitching

HR/FB - Home Run Rate

K/9 - Strikeout Rate

SIERA - Skill-Interactive ERA

WHIP - Walks plus Hits per Innings Pitched

FB% - Fly Ball Rate

GB% - Ground Ball Rate

LD% - Line Drive Rate

Miscellaneous

RAR - Runs Above Replacement

WAR - Wins Above Replacement (fWAR)

WE - Win Expectancy

WPA - Win Probability Added

Pythagorean Expectation by Bill James

Some readers may be unfamiliar with baseball statistics, especially the advanced sabermetrics variety. This is why I wanted to make a glossary available similar to Fangraphs, which is where the majority of these definitions are located.