Thank god for Billy Beane

Widely unknown and even less used until the mid-1990's, sabermetrics are high-level statistics used to evaluate and analyze baseball players of all positions. Nowadays, they are very commonly used by scouts and GM's to analyze both current professional players and prospects.\
Sabermetrics were rather uncommon and unknown until the GM of the Oakland A's, Billy Beane, famously rebuilt his team in the late 1990's using analysis provided by sabermetrics and pulled in "unknown" players that changed the face of the franchise (if you want to either read a good book about this or watch a good movie, the book Moneyball was just recently made into a movie. Brad Pitt plays Billy Beane). Nowadays, sites like Fangraphs are popular sites for sports nerds like myself to really go in-depth with their favorite players and see how they truly are doing-is the recent hot streak going to last? Is this breakthrough season for real? Are they possibly juicing (Melky Cabrera, I'm looking at you)?
Of course there are the more mainstream stats like ERA (Earned Run Average, a stat that identifies how many runs a given pitcher normally would give up in a 9-inning game), BA (Batting Average, how many hits a player will get in 10 at-bats), and WHIP (Walks/Hits per Inning Pitched, how many baserunners allowed per inning on average for a given pitcher). But sabermetrics go way beyond these. Here is a list of common sabermetric stats and their definition:

• WAR (Wins Above Replacement): how many more games, in a 162 game season, a given player will win over a minor-league callup playing in his place. Statistics are calculated differently for position players than for pitchers. For hitters, fielding and hitting is used. For pitching, hits, walks, and strikeouts are used.
• BABIP (Batting Average Balls In Play): used mainly to see if a hitter is getting "lucky" . A high BABIP usually signifies that regression might be coming, because this could mean that some balls in play are not getting caught when they should. On the other side, if a pitcher is giving up a high BABIP then oftentimes that signifies he is getting unlucky and that his other benchmarks are going to improve.
• FIP (Fielding-Independent Pitching): oftentimes considered by scouts as a better benchmark of a pitcher's performance than just straight ERA. This stat tracks what a pitcher's ERA would be if he played with a perfect defense. The idea is that after a ball is put in play the pitcher normally has no effect on the resulting play.
• UZR (Ultimate Zone Rating): basically measures a player's fielding over the performance of a benchmark "average" player. It analyzes the result of balls hit in play (hit/error/putout) in a given fielder's "zone" on the field and compares that to an "average" player's performance on a similar play.

Didn't know baseball got so technical, did you? Actually, these are some of the easier sabermetrics to understand. Baseball has become (at least even more so than in the past, as it has always been) a haven for statisticians. New stats are getting developed every year to better evaluate players and prospects. And an old-school game that hasn't changed too much in many aspects continues to experience a revolution.
And that's all I got.