I thought this would be a useful post for anyone who ever needs a quick reference for some of the stats that I use. Many of them you can’t find anywhere else (which gives you a huge advantage over your competition!), so explanations are definitely going to be necessary if you’re new to THT Fantasy Focus. Putting in a few minutes now to learn about these stats will be well worth the huge benefits you will reap from them.

###### Hitters – Contact stats

**Contact rate (CT%)** – The percentage of at-bats in which the hitter puts the ball in play, or how often he **doesn’t** strike out.

Importance: The more balls you can put in play, the more have a chance of falling for a hit. If you strike out, there is no chance of getting a hit.

**Batting Average on Balls in Play (BABIP)** – The percentage of balls in play that fall for hits.

Importance: Hitters have some control over it (each hitter tends to regress to his own unique level), but BABIP is prone to relatively severe random fluctuations, meaning a player can easily get either lucky or unlucky, potentially having a significant impact on batting average.

**Marcels Batting Average on Balls in Play (mBABIP)** – The BABIP that Marcels projects a player to hit going forward.

Importance: Since BABIP is unstable, the Marcels projection system gives us a truer estimate of a player’s true talent in this area. It applies a three-year weighted average with regression to the mean and an age curve.

**True Batting Average (tBA)** – The batting average a player *should* have posted.

Importance: Batting average is prone to fluctuations (due to the uncertain nature of BABIP and HR/FB), so tBA uses a player’s actual contact rate, mBABIP, and tHR/FB to arrive at an expected, true batting average.

###### Hitters – Plate discipline stats

**Judgment Index** – Essentially measures a hitter’s judgment of what pitches he should swing at and take.

Importance: A batter’s eye can be an important factor in determining his ability to see the ball well and make contact with it.

**Aggressiveness/Passivity (A/P)** – When a hitter does make a mistake in judgment, is it more likely to be a swinging mistake (aggressive) or a looking mistake (passive).

Importance: While all mistakes are bad, it’s better to make aggressive mistakes than passive mistakes.

**Bat Control** – Measures the percentage of pitches in the strike zone that a batter makes contact with, given that he swings at it.

Importance: Since balls in the strike zone are generally hittable, batters who are able to make high contact on their in-zone swings have good control of the bat.

**Bad Ball Hitting** – Measures the percentage of pitches outside the strike zone that a batter makes contact with, given that he swings at it.

Importance: While swinging at balls outside the zone is generally not a very good idea, hitters who are good “bad ball” hitters will do much better than those who aren’t when they do swing at pitches outside the zone.

Click here for a more detailed description of these plate discipline stats.

###### Hitters – Power stats

**Outfield fly ball rate (OF FB%)** – The percentage of balls in play that are outfield fly balls.

Importance: You can’t hit a home run if the ball isn’t hit into the outfield, in the air.

**Home run per fly ball (HR/FB)** – The percentage of outfield fly balls that are home runs, which hitters have a good amount of control over.

Importance: Combined with OF FB%, a pretty good measure of a hitter’s power independent of the number of at-bats accumulated.

**True Home run per fly ball (tHR/FB)** – The percentage of outfield fly balls that *should* have become home runs.

Importance: While hitters have some control over actual HR/FB, tHR/FB uses HitTracker data (how far the ball is hit, specific park dimensions, weather effects) to show how many home runs should have been hit given a 50/50 home/road split and neutralized weather conditions. The full methodology can be found here.

**Park-neutral Home run per fly ball (nHR/FB)** – The percentage of outfield fly balls that would have become home runs in a league average park with neutral weather.

Importance: Useful to see how a hitter’s power would fare in a neutral situation, especially for those who could be traded. If lower than tHR/FB, the hitter’s home park helps him. If higher, his home park hurts him.

###### Hitters – Speed stats

**Stolen base opportunity percentage (SBO%)** – How often the hitter reaches first base (excluding intentional walks).

Importance: The majority of steals occur when hitters steal second, but you can’t steal second unless you reach first safely.

**Stolen base attempt percentage (SBA%)** – How often the hitter attempts to steal given the number of times he reaches first safely.

Importance: You can’t steal a base unless you leave first, can you? The more often you try, the more often you’ll succeed.

**Stolen base success percentage (SB%)** – How often the hitter successfully steals a base given his number of attempts.

Importance: Once you know how often a hitter is in position to steal and how often he tries to once in that position, the final piece of the puzzle is how often he succeeds.

**Fan Speed Score** – The speed of a player (on a scale of 1-to-100) as measured by Tom Tango’s Fan Scouting Report.

Importance: Speed is one component of a player’s ability to successfully steal a base, and the Fan Speed Scores are a good predictor of stolen base success.

###### Pitchers – Skills

**Strikeout rate (K/9)** – The percentage of strikeouts a pitcher accumulates per nine innings pitched.

Importance: When a strikeout occurs, the ball is not put in play, which eliminates the possibility of a pitcher getting unlucky (see: BABIP). A strikeout is a guaranteed out that a pitcher has ultimate control over.

**Walk rate (BB/9)** – The percentage of walks a pitcher accumulates per nine innings pitched.

Importance: Like strikeouts, a pitcher has ultimate control over walks. Unlike strikeouts, walks are bad. The more batters walked, the easier it becomes for the other team to score.

**Run Impact from strikeouts and walks (K-BB RI)** – The relative number of runs a pitcher’s strikeouts and walks either save or cause.

Importance: Serves the same purpose of strikeout-to-walk ratio (K/BB), to measure the impact of two most important isolated pitching statistics on the number of runs a pitcher allows, but this stat more accurately measures that impact since a strikeout and a walk are not worth the same amount.

**Ground ball percentage (GB%)** – The percentage of ground balls a pitcher induces per ball in play, which a pitcher has a lot of control over.

Importance: If the ball is hit on the ground, it can’t become a home run. Not as good as a strikeout, but far preferable to a fly ball that could quickly put runs on the board.

**Expected ground ball percentage (xGB%)** – The percentage of ground balls a pitcher would induce per ball in play after normalizing line drive rate.

Importance: More accurate than actual GB% since allow too many or too few line drives will either increase or decrease GB% artificially.

###### Pitchers – Luck indicators

**Batting Average on Balls in Play (BABIP)** – The percentage of balls in play that fall for hits.

Importance: Pitchers have very little control over BABIP, making them prone to even more random fluctuations than hitters. These fluctuations can have a significant affect on the number of hits the pitcher gives up, impacting WHIP and ERA. Most pitcher regress to league average (around .300), but some elite pitchers can maintain BABIPs as low as .280.

**Line drive percentage (LD%)** – The percentage of line drives a pitcher induces per ball in play, which a pitcher doesn’t have much control over.

Importance: Line drives become hits at the highest rate of any type of ball in play. Because pitchers can’t really control how many they give up, those who give up too many or too few are prone to either getting lucky or unlucky with their hits allowed (and BABIP).

**Home runs per fly ball (HR/FB)** – The percentage of fly balls that are home runs, which pitchers don’t have much control over.

Importance: Home runs are automatic earned runs, so pitchers who get lucky or unlucky in this category can have drastically higher or lower ERAs.

**Left on base percentage (LOB%)** – The percentage of batters who reach base that the pitcher allows to ultimately score, a stat that pitchers have limited control over.

Importance: Pitchers have more control over this stat than BABIP or HR/FB, but those who have extreme rates will either have higher or lower ERAs than they deserve.

**Run support (RS)** – The average numbers of runs per game a pitcher’s team’s offense scores on the days he pitches.

Importance: The most important factor in whether or not a pitcher gets a win is how many runs his team scores for him, which is something he has little effect on. Pitchers who have less run support than his team’s average should win more games going forward, and visa-versa as luck evens out.

###### Pitchers – Comprehensive stats

** Luck Independent ERA (LIPS ERA)** – The ERA we should expect a pitcher to have based on his peripheral stats (strikeouts, walks, ground balls, etc.) and a normal distribution of luck.

Importance: Mirrors ERA and gives a much more accurate depiction of the pitcher’s true skill level.

**Defense Independent WHIP (DIPS WHIP)** – The WHIP we should expect a pitcher to have based on his walk rate, a normalized line drive rate, and a normal distribution of hits for each batted ball type.

Importance: Mirrors WHIP and gives a much more accurate depiction of the pitcher’s true skill level in preventing base runners.

**True Quality Starts (TQS)** – Uses grades of Great, Good, Above Average, Below Average, Bad, and Poor to determine the quality of each of a pitcher’s starts using only his peripheral skills (K, BB, and xGB) and innings pitched.

Importance: Potentially useful for finding players with hidden talent that perhaps isn’t shown in the overall numbers because of inconsistency in the form of some poor starts. Click here to read the full methodology.