Fantasy Baseball Sabermetric Statistics: Your Not-So-Advanced Guide to Advanced Stats

by Jonathan Chan
fantasy baseball sabermetric statistics

Welcome to the Fantasy Six Pack guide on Fantasy Baseball Sabermetric Statistics.

Fantasy Baseball, more than any other sport, makes use of advanced statistics to determine player value. Prediction of future performance is based on more than just playing time or teammate quality.

If you've ever been in a Fantasy Baseball league, you have no doubt seen statistics like BABIP, xFIP, and more recently, wOBA being thrown around. For new players, seeing stats on top of stats can be overwhelming.

Applying all of these measures takes time to get used to. Having to analyze the underlying reasons for players' production takes dedication, but can bring plenty of rewards for those who know what to look for. Using sabermetrics can help managers predict who's lucky and who can sustain their performance. Some players will defy the logic behind these stats. However, understanding how to use advanced stats will give you an advantage in your league.

This guide will give an overview of the most common sabermetric stats used by the Fantasy community. Each statistic will come with a definition and an explanation on how to use it to evaluate players.

Fantasy Baseball Sabermetric Statistics

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Offensive Statistics

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Batting Average on Balls in Play (BABIP)

BABIP is the most commonly used advanced statistic in baseball. Simply, it measures a player's batting average on all non-home run balls they put in play. BABIP is commonly used as a "luck" statistic. League average BABIP is .300, therefore, players with a BABIP of .340 may be lucky and their performance may regress.

However, BABIP involves much more than just luck. BABIP involves defensive performance and the talent level of the batter and pitcher.

Some players' skill sets will lead to a naturally higher or lower "baseline" BABIP. There are several major instances of this happening:

  1. Speedy players will naturally carry a higher BABIP, as they have the speed to beat out ground balls that other players wouldn't.
  2. Players who hit a high percentage of fly balls will tend to have lower BABIP because:
    • Fly balls are easier outs.
    • Heavy fly ball hitters tend to hit more home runs, which do not factor into BABIP calculation.
  3. Players who hit a large number of line drives will have higher BABIP as they fall for hits more often than ground balls or fly balls.

Overall, BABIP can be used to determine the overall sustainability of a batter's performance. If their BABIP is significantly higher or lower than their career average, regression to the mean can be expected.

Batted Ball Profiles

Batted ball profiles give you an idea of the kind of contact a batter is making. A complete profile includes the following metrics:

  • Fly-ball (FB) %
  • Ground-ball (GB) %
  • Line-drive (LD) %
  • Infield-flyball (IFFB) %
  • Quality of Contact
    • Soft %
    • Medium %
    • Hard %

Generally, you want players to produce a higher LD%, as those lead to more hits and more production. A higher FB% is more favorable than a high GB% because fly-balls produce home runs.

Quality of contact statistics are incredibly useful, as they give us an idea of the kind of balls a batter is putting into play. Of course, a high hard-hit percentage doesn't automatically translate into production, but more hard-hit balls generally translate into more total bases and a better batting line. Managers should use quality of contact stats to determine the quality of the swings batters are generating. A higher hard% and LD% mean a higher quality of balls being put into play.

While contact profiles can give a good idea of how a better is performing, there is no perfect profile to predict success. Batters will find success with a variety of batted ball profiles.

Weighted On Base Average (wOBA)

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wOBA is one of the best all-around offensive statistics out there. It's used to measure a hitter's overall value, based on the relative value of each offensive outcome. wOBA takes into account that some hits are more valuable than others.

According to FanGraphs, the formula for wOBA in 2013:

wOBA = (0.690×uBB + 0.722×HBP + 0.888×1B + 1.271×2B + 1.616×3B +
2.101×HR) / (AB + BB – IBB + SF + HBP)

Moreso than OPS, wOBA gives a more comprehensive analysis of a player's contributions to run-scoring. OPS undervalues a player's ability to get on base, while not properly weighing the value of each extra-base hit. WOBA is scaled to league average OBP, so if you're familiar with what a good OBP is, you'll know what a good wOBA is. Typically, the league average wOBA will sit around .320. 20 points of wOBA generally results in an extra 10 runs above average per 600 plate appearances.

Weighted Runs Created (wRC+)

This stat measures exactly what it says: The value of a hitter based on the number of runs he creates. wRC+ is very similar to wOBA in that it is an overview of a player's prowess at the plate. It goes one step further than wOBA, in that it measures the effects of park factors on a batter's performance.

It is measured on a scale where 100 is the league average. This means a player with a wRC+ of 120 is 20 percentage points better than the league average at creating runs.

Barrels

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A “Barrel” is used to classify a batted ball event where similar hit types (in terms of exit velocity and launch angle) have led to a minimum .500 batting average and 1.500 slugging percentage.

To be barrelled, a batted ball needs an exit velocity of at least 98 MPH. At that speed, any ball with a launch angle between 26-30 degrees will always be classified as a barrel. For each MPH over 98, the launch angle to be classified as a barrel expands.

A player’s Barrell rate indicates what percentage of their batted balls can be classified as barrels.

The more barrels a player produces, the more power production they will provide.

O-Swing/Contact, Z-Swing/Contact Percentage

O-Swing% is the percentage of swings a batter takes at pitches outside the zone. O-Contact% is the percentage of those swings that a batter makes contact on. MLB average for O-Swing is 30%, while O-Contact is 66%.

Z-Swing% is the percentage of swings a batter takes at pitches inside the zone. Z-Contact% is the percentage of those swings that a batter makes contact on. MLB average for Z-Swing is 65%, while Z-Contact is 87%.

These plate discipline stats are important for determining a player’s approach. It allows us to see how passive or aggressive a player is at the plate and their success level based on that approach.

Plate discipline numbers should be used in the context of other statistics. Making contact on lots of pitches outside the zone looks great on the surface, but the result of those batted balls needs to be taken into account.

While a high contact rate is good in general, remember there is no “ideal” plate discipline profile.

Pitching Statistics

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Fielding Independent Pitching (FIP) and xFIP

FIP measures what a pitcher's ERA would look like if they had experienced league average fielding percentage and results on balls in play. Research by Voros McCracken revealed that pitchers have little control over balls in play, meaning that fluctuations in their ERA due to slight changes in BABIP are not attributable to the pitcher.

FIP is a direct measurement of the pitcher's performance without the influence of defensive performance and luck, making it a more stable indicator of a pitcher's true performance. It's a better way of isolating a pitcher's true performance than ERA. FIP isolates a pitcher's performance based on their strikeouts, walks, hit batters, and home runs allowed, things that the pitcher can directly control. FIP is a great way to measure the future performance of a pitcher, rather than past performance.

xFIP is a regressed version of FIP that replaces the pitcher's home run total with the total they should have given up based on the number of fly balls they gave up. This is done by replacing their HR/FB ratio with the league average number.

Skill-Interactive ERA (SIERA)

SIERA, like FIP and xFIP, is another ERA predictor. SIERA also takes fielding and BABIP into account but, unlike FIP and xFIP, it also accounts for the type of balls put into play against the pitcher.

For example, a pitcher with a high xFIP might have also generated a lot of groundballs and pop-ups, the kind of contact a pitcher should hope for, therefore giving them a lower SIERA than xFIP.

SIERA is scaled to ERA, so the lower the score, the better. Used alongside FIP and xFIP, managers have three solid ways of predicting a pitcher's future performance.

Batting Average on Balls in Play (BABIP)

BABIP may be even more important in evaluating pitchers than evaluating batters. Once the ball leaves the bat the pitcher has little to no control over the outcome. Pitcher BABIP is heavily influenced by defense and luck. Therefore, pitchers that have a high BABIP may be a victim of poor defense or bad luck.

Over the course of a season, an average pitcher's BABIP is around .300. If a pitcher's BABIP is significantly higher than average, his opponent's batting average will increase, and poor results will follow. This is where managers need to verify the pitchers' results using other, defense-independent, stats like FIP and xFIP.

Most pitchers have a full-season BABIP of around .290-to-.310. If a pitcher is carrying a BABIP too far away from .300 or their career average, expect some regression to the mean over the remainder of the season.

K/9 and BB/9

Strikeout rates and walk rates are simple stats that are incredibly helpful when evaluating a pitcher's performance. K/9 represents the number of strikeouts a pitcher accumulates every nine innings, while BB/9 is the number of walks per nine innings. Of course, the goal for pitchers is to strike out more batters while walking fewer

Generally, managers will want to find pitchers with a high K/BB ratio. Pitchers with more control and the ability to strike people out will be less at the mercy of BABIP as fewer people will be on base and fewer batters will put the ball into play.

Batted Ball Profiles

Batted ball profiles are used in the same way for pitchers. If someone is allowing a lot of hard contact or a high LD%, it's likely their stat lines will reflect that batters are able to make good contact with their pitches.


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