Once you really dive into fantasy baseball, you'll discover that there is a world of stats available that you may not be immediately familiar with. This page lists some definitions and insight on some of the most commonly-used stats out there. If you'd like to see a definition added, please let us know.
Batting Average On Balls In Play
(Hits - Home Runs)/(At Bats - Strikeouts - Home Runs)
Hitters tend to track to their own career hit rate. If they are far over or under their career rate, then they're due for a correction usually (unless they've changed something).
Hitters closer to 1-to-1 are ideal, but mostly you're looking to avoid the really poor hitters with worse than 1-to-2 ratios.
Walks/(At Bats + Walks)
A good gauge of a hitter's plate discipline. Look for hitters over 10%.
Walks Allowed Per 9 Innings
(Walks Allowed/Innings Pitched) * 9
Look for pitchers who walk less than 3.00 batters per nine innings. Note, the NL is going to have a higher walk rate, simply because the intentional walk is used more frequently.
(At Bats - Strikeouts)/At Bats
Hitters who put balls in play at 90% or above are ideal, 75% or lower could result in poor batting averages.
Fielding Independent Pitching
((Home Runs * 13) + ((Walks + Hit By Pitch) * 3) - (Strikeouts * 2))/(Innings Pitched + 3.2)
Fielding Indpendent Pitching (FIP) is a defense neutral ERA. In general, a pitcher with a FIP higher than his ERA is likely getting lucky with his balls that are put in play. The exception is if the defense behind the pitcher is above average, which would cause more batted balls to be converted into outs.
Ground Ball to Fly Ball Ratio
Ground Ball Outs/Fly Ball Outs
A strong ground-ball pitcher can overcome a low strikeout rate, while a fly-ball pitcher will often need a deep ballpark to be successful.
Home Runs Allowed Per 9 Innings
(Home Runs Allowed/Innings Pitched) * 9
The league average is usually a little above one home run allowed per nine innings. Consider avoiding pitchers who consistently end up well above that number.
Look for pitchers who strike out 2.5 or more batters per walk.
Strikeouts Per 9 Innings
(Strikeouts/Innings Pitched) * 9
Look for starters who strike out 7 or more hitters per nine innings. For relievers, you'll want to aim a bit higher and find pitchers who can exceed 8.5 strikeouts per nine innings.
On Base Percentage + Slugging Percentage
OBP + SLG
The league average is in the .750 range. What you should be looking for is highly dependent on position. For example, a lower OPS is more acceptable from a shortstop than an outfielder or first baseman.
Stolen Base Opportunity
(Stolen Bases + Caught Stealing)/(Singles + Walks)
This is a measure of how often a hitter will take advantage of stolen base opportunities. Baserunners who get the green light usually average .20 or above.
(Hits + Walks Allowed - Earned Runs)/(Hits + Walks Allowed - Home Runs)
Strand rate is the percentage of batters that reach base but do not score. Pitchers with Strand Rates above .75 are usually successful with a decent ERA. Watch for deviations from a pitchers career strand rate. For example, a pitcher who has a career strand rate of 71% but 85% strand rate this season may be getting a little lucky.
Walks + Hits Per Inning
(Walks Allowed + Hits Allowed + Hit By Pitch)/Innings Pitched
This stat gives an idea of how many batters a pitcher puts on base. Look for pitchers under 1.25 and try to avoid those over 1.40.