You can use this page as a reference for interpreting many of the more advanced stats used in the articles.
In many of the article you will see a batter described by his triple slash. It will be in the form .xxx/.xxx/.xxx where the first number is batting average, the second number is on base percentage, and the last number is slugging percentage. I will assume most people know how to interpret batting average, so I will just describe OBP (on base %) and SLG (Slugging %).
OBP: The most important thing a hitter can do is not get out. If you ever watched the movie “Moneyball”, OBP is the foundation in which the “Moneyball” strategy was based on. The formula is as follows:
H = hits BB = walks HBP = Hit by pitch AB = At bat SF = Sacrifice
Here is a chart from Fangraphs that shows how to interpret a given OBP:
SLG%: Slugging, or SLG for short, is the measure of a players’ power. In other words, the higher a players’ SLG, the more power he has displayed in terms of bases covered. It is simply the number of bases covered per AB.
BABIP: I use BABIP fair amount when describing both hitters and pitchers. It is the rate at which the batter gets a hit when he puts the ball in play. I can be used to indicate, for example, when a certain hitter is having a bit of bad luck. A hitter may hit the ball hard consistently but if it is right at a player you could say he has been getting unlucky. Thus if you compare a players actual batting average to his BABIP and the BAPIP is much higher you could project the players average to rise as he will likely see more ball drop. For example:
Most players will have BABIP above their average, however the extent makes a difference. Read BABIP like regular average. In Braun’s case his BABIP of .274 is not too high and it would be like saying that if all of the balls Braun put in play were to fall in for a hit, he would be a .274 hitter. On the other hand, Yelich had the 2nd best BABIP in all of baseball with .373 which helped his actual average to be as high as it was. A BABIP that high is not maintainable. This is why breakout hitters who have a high BABIP tend to project worse the next season.
K% and BB%:
The amount of strikeouts or walks per plate appearances.
wOBA: Weighted On Base Average
This is an advanced formula with the purpose of being an all encompassing offensive stat. It uses weights that change by year in an attempt to more accurately quantify which offensive metrics mean more or less compared to others. Here is the 2013 formula:
And here is how you interpret wOBA:
wRC+: Weighted Runs Created Plus
You will see this metric a lot in articles. It attempts to give the hitter credit for the value of each hit as opposed to having each hit count the same. In addition this takes the run scoring environment into account with a ballpark factor that attempts to balance the playing fields. For example it will balance the players who plays in Coors Field (hitter friendly park) and the players who play in Kaufmann Stadium pitcher friendly park). The formula is as follows:
And the interpretation is as follows:
The thing to keep in mind is that 100 is average and any above or below the the percentage better or worse than average. For example, Yelich had a wRC+ of 166, meaning he created 66% more runs than the league average hitter would have given the same number of plate appearances.
O-Swing%: Outside the zone swing percentage
The number of times the batter swings at a pitch outside the zone divided by the number of total pitches outside the zone.
Z-Swing%: Inside the zone swing percentage
The number of times the batter swings at a pitch in the zone divided by the number of total pitches inside the zone.
O-Contact%: Outside the zone contact percentage
The number of times the batter made contact with a pitch outside the zone divided by the total number of swings at pitches outside the zone.
Z-Contact%: Inside the zone contact percentage
The number of times the batter made contact with a pitch in the zone divided by the total number of swings at a pitch inside the zone.
F-Strike%: First pitch strike percentage:
Percentage of PA that begin with a strike. This could be used to see what pitchers get ahead in the count most often, or to see what hitters prefer to take the first pitch of a PA.
SwStr%: Swinging strike percentage:
Number of total swinging strikes divided by total pitches.
WAR: Wins Above Replacement
The all encompassing stat that attempts to quantify how many wins a player is worth given offensive, defensive, and base running abilities. Here is the formula:
Seems easy, but most of the components of this formula require a formula of their own just to plug into this one. WAR adjusts for position, league, ballpark, and league averages. Here is how you would interpret WAR:
In many cases the MVP has a higher WAR. To put it in context, Mookie Betts won the 2018 MVP with a 10.4 WAR. Yelich had the highest NL WAR with 7.6 and that was 6th in all of MLB.
The visuals are via Fangraphs, and a full glossary with more detail and explanation can be found on Fangraphs. You can find the link on the Sites and Applications page here at Statsswipe.