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Sabermetric stats primer

FIP, xFIP, BABIP and WAR ... I can't take it anymore!

We're in the midst of baseball's statistical revolution, and as we delve deeper into the 21st century, there seems to be an increasingly endless supply of measures a fantasy baseball owner can use to judge player value. As you'll read throughout our Draft Kit, in player profiles, in columns and in our videos this season, we're always pointing out useful metrics to help inform your decisions.

But the fantasy baseball community is a group with varying experience. Some are advanced to the point that they're inventing their own measures. Others might be new to the game, perhaps even unfamiliar with a basic Rotisserie concept such as WHIP -- Walks plus Hits divided by Innings Pitched, for those unfamiliar. At some point during the course of 2015, we might drop a term or concept onto our pages with which you're less familiar.

That's where this column comes in. Listed below are some of the most commonly cited metrics in fantasy baseball, a reference guide, if you will, to the meanings and calculations behind some of the more complex categories.

Quick click by stat category: WAR | BABIP | FIP | xFIP | HHAV | wOBA | HR/FB% | Miss% | SwStr% | LOB% | ISO | Batted ball rates | Chase% | K/9 versus K%

WAR (Wins Above Replacement): One of the more controversial statistical innovations of the 21st century, WAR attempts to summarize a player's total contributions -- hitting, base running and fielding for hitters, and pitching performance usually using FIP-like factors (FIP is explained below) for pitchers -- relative to replacement level, which is the statistical equivalent of a typical player who would be summoned from the minors as a stand-in. WAR tends to cause controversy for a multitude of reasons, most notably that it lacks a universal calculation; hundreds of calculations are involved and, since different sources disagree on particular parts, players can have different WAR depending upon the source you choose. ESPN uses Baseball-Reference.com's WAR calculation, and you can read more about their methodology here.

In fantasy baseball terms, WAR can be a misleading measure, because of the inclusion of defense, which is included in a small percentage of leagues. For example, Jason Heyward (6.35) had the majors' 17th-best WAR in 2014, but most of that was driven by what was the fifth-best defensive WAR (2.83); defensive WAR is often called "dWAR." Extracting only Heyward's offensive contributions, or in this case "oWAR," he was the 76th-best hitter (2.79 oWAR), which is considerably closer to his final 2014 Player Rater ranking (73rd). That's not to say that every player's oWAR will mirror his Player Rater ranking, but if you're using a WAR measure to evaluate players for fantasy, oWAR is a much better place to start. The formula: See the above link for Baseball-Reference.com's calculation, and go here for Fangraphs' version.

2014 WAR leaderboard (plus Player Rater comparison)

Listed below are 2014's top 20 performers in terms of oWAR (hitters), on the left, and WAR (pitchers), on the right, as well as their relative ranking among hitters and pitchers on the Player Rater ("PR"). Top-20 hitters and pitchers on the Player Rater are also included to show their oWAR/WAR rankings.

Batting Average on Balls In Play (BABIP): A statistic whose fundamentals are widely credited to Voros McCracken, BABIP measures the rate of batted balls put into the field of play that resulted in hits. It is the effective equivalent of a hitter's batting average or pitcher's batting average allowed, only in plate appearances resulting in a ball batted into the field of play (home runs excluded, as they leave the field of play). BABIP has been one of the more popular fantasy baseball innovations of the past decade, but it has also led to an increase of misinterpretation of its use; I have discussed this on numerous occasions in the past, most recently in 2013.

Most often, fantasy owners ignore the influences of types of contact on BABIP -- this is also discussed below under "Batted ball rates" -- as ground balls, fly balls, line drives, pop-ups and bunts affect BABIP at varying rates, as does the quality of contact of the batted ball -- also discussed further below under "Hard Hit Average." Major League Baseball's average BABIP last season was .299 and it has been within six points of that number in every season since 1992; it is typically, however, close to .250 on ground balls (so roughly one of every four of those results in a hit), .100 on fly balls and .675 on line drives, and .625 on batted balls that were judged "hard contact" by ESPN's video-review service. If a player has an unusually high or low BABIP, before assuming he was heavily influenced by "luck" -- a mistake many fantasy owners make -- investigate whether it might have been the product of a greater number of a particular type of batted ball. The formula: Hits minus home runs, divided by at-bats minus home runs minus strikeouts plus sacrifice flies -- or (H - HR)/(AB - HR - K + SF).

Listed below are 2014's top and bottom 10 qualified hitters in terms of BABIP. Their batting averages, including their rank in that category, as well as their Hard Hit Averages and batted-ball rates are also included for further perspective.

Listed below are 2014's top and bottom 10 qualified pitchers in terms of BABIP. Their batting averages allowed, as well as their Hard Hit Averages and batted-ball rates, are also included for further perspective.

Fielding Independent Pitching score (FIP): Its creation credited to both Tom Tango, who named it "FIP," and Clay Dreslough, who had a similar calculation he called "Defensive Independent Component ERA (DICE)" that he used in his computer baseball game, FIP attempts to measure what a pitcher's ERA should have been, based upon his performance in the categories he can most control, strikeouts, walks and home runs allowed. It puts this measure onto an ERA scale, attempting to eliminate random variance and extreme defensive influences from a pitcher's performance.

A pitcher with a FIP considerably lower than his ERA might be termed to have been "unlucky" in the given time span, while one with a higher FIP than ERA might be described as having had good fortune. The formula: Home runs times 13 plus three times walks plus hit batsmen minus two times strikeouts, divided by innings pitched, plus a league constant to assure that the league's average FIP equals the league's average ERA -- or ((13 * HR) + (3 * (BB + HBP)) - (2 * K)) / IP + league constant.

Listed below are 2014's top and bottom 10 qualified performers in terms of FIP, with starting pitchers on the left and relief pitchers on the right. Top and bottom 10 performers in ERA are also included to show their FIP rankings.

Expected Fielding Independent Pitching score (xFIP): Created by Dave Studeman of The Hardball Times, xFIP utilizes the FIP formula but instead regresses a pitcher's home run rate to the league's mean. Instead of using the pitcher's homer total allowed, it replaces that part of the equation with an estimate of the number of homers he should've surrendered had the fly balls he allowed cleared the fence at the league's average rate (generally around 10 percent). xFIP takes FIP one step further, attempting to eliminate another "luck" factor from the equation. The formula: The same as FIP, except that home runs are replaced by fly balls times the league's home run/fly ball percentage -- or ((13 * FB * league-average HR/FB%) + (3 * (BB + HBP)) - (2 * K)) / IP + league constant.

Listed below are 2014's top and bottom 10 qualified performers in terms of xFIP, with starting pitchers on the left and relief pitchers on the right. Top and bottom 10 performers in ERA are also included to show their xFIP rankings.

Hard Hit Average (HHAV): Formerly known as "Well Hit Average (WHAV)," this measures the percentage of a player's at-bats -- whether a batter's own or those a pitcher affords to opposing batters -- that resulted in hard contact. ESPN uses a service that reviews video of every plate appearance and rates batted balls as either hard, medium or soft hit, judging those based upon velocity, distance and sweet-spot contact. There is also a statistic for the converse of this statistic; it is called Soft Hit Average, or SHAV.

While Hard Hit Average doesn't have a direct correlation to fantasy value, it does help identify a hitter's ability with the bat, especially his power potential, as well as a pitcher's stuff, particularly how difficult it is to hit. The formula: Hard hit balls divided by at-bats -- or HH / AB. For Soft Hit Average, it would be soft hit balls divided by at-bats -- or SH / AB.

Listed below are 2014's top and bottom 10 performers in terms of HHAV, hitters on the left and pitchers on the right. Hitters' batting averages and home runs, and pitchers' ERAs and strikeout rates, are also included for further perspective.

Weighted On-Base Average (wOBA): Another creation of Tom Tango's and one published in "The Book," released in 2006, wOBA aims to measure a player's overall contributions per plate appearance, whether hitters' own performance or a pitcher's performance allowed to opposing hitters. It is based on linear weights, taking run expectations of certain offensive events like total bases, non-intentional walks and times hit by pitch. It is a particular favorite of mine, ahead of the more commonly cited OPS, because it combines the many positive offensive contributions a hitter can influence into a rate statistic calculated per plate appearance; OPS' weakness is that it combines two ratio statistics that utilize different denominators (slugging percentage, which uses a percentage of at-bats, and on-base percentage, which adds walks, hit by pitch and sacrifice flies to the at-bat denominator).

wOBA can be a useful tool in sabermetrically angled fantasy baseball leagues, such as those which reward for walks or on-base percentage, as well as points-based leagues because of its reward for extra-base hits. It does not, however, account for stolen bases, making it a weaker tool for Rotisserie 5x5 valuation. The formula: A league constant for each category is multiplied against non-intentional walks, times hit by pitch, singles, doubles, triples and home runs and these are then totaled, and divided by at-bats plus walks minus intentional walks plus sacrifice flies plus times hit by pitch -- or (constant * (BB - IBB) + constant * HB + constant * 1B + constant * 2B + constant * 3B + constant * HR) / (AB + BB - IBB + SF + HB). For the 2014 season, these constants were 0.689 for non-intentional walks, .722 for HB, .892 for 1B, 1.283 for 2B, 1.635 for 3B and 2.135 for HR, and annual constants can be seen here.

2014 wOBA leaderboard (plus Player Rater comparison)

Listed below are 2014's top and bottom 10 performers in terms of wOBA, hitters on the left and pitchers on the right, as well as their relative ranking among hitters and pitchers on the Player Rater ("PR"). Top-10 hitters and pitchers on the Player Rater are also included to show their wOBA rankings.

Note: Holland's wOBA ranking is among qualified relief pitchers.

Home Run to Fly Ball rate (HR/FB%): Another measure fantasy owners traditionally use to gauge the influence of "luck" on a player's statistics, this represents the ratio of a player's fly balls that cleared the fence for a home run. If a player hit an unusually large number of home runs -- as Chase Headley did when he hit 23 in the second half of 2012 -- it might be worth examining his HR/FB% to determine whether the performance was sustainable. Headley's 29.5 percent rate in that half-season demonstrated it wasn't. The league's average Home Run to Fly Ball rate in 2014 was 10.2 percent, and is typically close to 10 percent most seasons. Remember, though, to consider ballpark factors when judging this category, as certain parks have greater rates than others. The formula: Home runs divided by total fly balls (which includes line-drive home runs) -- or HR / (FB + LD HR). For greater accuracy, if you have access to inside-the-park home run totals, subtract them from the numerator.

Listed below are 2014's top 20 hitters in terms of HR/FB% on the left, and top and bottom 10 pitchers in terms of HR/FB% on the right. Their 2014 home run totals as well as their 2010-14 combined HR/FB% are also included for further perspective.

Miss rate (Miss%): Or "swing and miss" rate, or the reverse of FanGraphs' Contact rate (Contact%), this is the percentage of a batter's swings that resulted in a flat-out miss. Miss rate can be a handy tool for evaluating a hitters' penchant for strikeouts, or how unhittable a pitcher's raw stuff. Keep in mind, however, that certain players have differing Miss rates depending upon the count; this can often hint a hitter's tendency to shorten his swing with two strikes, or a pitcher lacking a two-strike "put-away" pitch. The league's average Miss rate in 2014 was 22.5 percent, and it is typically around 22 percent most seasons. The formula: Misses divided by total swings. To calculate Miss rate using FanGraphs data, subtract their Contact% from 100.

Listed below are 2014's top and bottom 10 performers in terms of Miss%, hitters on the left and pitchers on the right. Hitters' and pitchers' strikeout rates are also included for further perspective.

Swinging Strike rate (SwStr%): It's somewhat like Miss rate, except that it's calculated as a percentage of total pitches seen, rather than swings. Using the two statistics in conjunction can identify whether a high-strikeout hitter has a keener sense of the strike zone, or a pitcher's stuff is both difficult to hit and deceptive. It is worse for a hitter to have a higher number (relative to the league average) in Swinging Strike rate rather than Miss rate, just as it's better for a pitcher to have a higher Swinging Strike rate rather than Miss rate. The league's average Swinging Strike rate in 2014 was 10.4 percent, and it is typically around 10 percent most seasons. The formula: Misses divided by total pitches seen.

Listed below are 2014's top and bottom 10 performers in terms of SwStr%, hitters on the left and pitchers on the right. Hitters' and pitchers' strikeout rates are also included for further perspective.

Left On Base Percentage (LOB%): Also termed "Strand Rate" by its inventor, Ron Shandler, this measures the percentage of base runners afforded by a pitcher that he prevented from scoring. It is not a calculation based upon standard "left on base" data available in box scores; it instead uses only traditional measures that a pitcher can control. Left On Base Percentage can often indicate two specific things: One, an unusually "lucky" or "unlucky" season, or two, a wider split in the pitcher's ability to work with either the bases empty (typically the windup) or with men on base (typically from the stretch). If a pitcher has a Left On Base Percentage significantly removed from the league average -- it was 73.0 percent in 2014, but typically ranges between 70-73 percent -- consider first examining his statistical splits with men on base versus with the bases empty. The formula: Hits plus walks plus hit batsmen minus runs, divided by hits plus walks plus hit batsmen minus home runs multiplied by 1.4 -- or (H + BB + HB - R)/(H + BB + HB - (HR * 1.4)).

Listed below are 2014's top and bottom 10 qualified performers in terms of LOB%, with starting pitchers on the left and relief pitchers on the right. Top and bottom 10 performers in ERA are also included to show their LOB% rankings.

Isolated power (ISO): A tool that assists in measuring a hitter's raw power, Isolated power shows how often a player generated extra-base hits rather than singles. Using it in conjunction with Hard Hit Average and Fly Ball rate -- that discussed more below -- can help identify underrated power sources, and provides for better analysis than idle fantasy baseball statements like, "He hit 50 doubles last season, some of those might start clearing the fence this year." Generally speaking, .200-plus Isolated power would be regarded "elite." The formula: Slugging percentage minus batting average -- SLG - AVG -- or total bases minus hits divided by at-bats -- (TB - H)/AB.

Listed below are 2014's top 20 hitters in terms of ISO in the left two columns, and bottom 10 hitters in terms of ISO in the right-hand column.

Batted ball rates: Ground Ball (GB%), Fly Ball (FB%) and Line Drive (LD%) rates: Each is a separate calculation of the percentage of a player's batted balls -- including home runs, in this case -- that are ground balls, fly balls and line drives. Depending upon the source, pop ups, bunts and infield fly balls are often also differentiated. For ESPN's purposes, Ground Ball, Fly Ball and Line Drive rates use results from our video-review service, and can differ slightly from other sources like FanGraphs.

Such batted-ball splits can help judge hitters' skills, as line drives result in (by far) the greatest hit rate, followed by bunts, ground balls, fly balls and then pop ups. However, keep in mind that fly balls are especially valuable because they can result in home runs; this is why a higher ground ball rate can be better for a pitcher. Bunts, too, have a higher hit rate primarily because the players who utilize them tend to be speedy types who can run them out. Formulas for these use calculations as a percentage of all balls in play.

Listed below are 2014's top and bottom 10 qualified hitters broken down by rate of differing types of batted balls: GB%, FB% and LD%.

Listed below are 2014's top and bottom 10 qualified pitchers broken down by rate of differing types of batted balls: GB%, FB% and LD%.

Chase rate (Chase%): It's the percentage of pitches judged by ESPN's video-review service as "outside the strike zone" at which the batter swung, regardless of the result of the play, and it is a good indicator of a hitter's plate discipline and a pitcher's deceptiveness. This is also sometimes called Outside the Zone Swing rate, or "O-Swing%," on sites like FanGraphs, and it can differ depending upon the source. The formula: Swings at pitches outside the strike zone divided by total pitches outside the strike zone.