Understanding FIP (Fielding Independent Pitching) for Blue Jays
In the data-driven world of modern baseball, traditional statistics like ERA (Earned Run Average) only tell part of the story of a pitcher's performance. To isolate a pitcher's effectiveness from the defense behind them, analysts and front offices, including the Toronto Blue Jays', turn to more advanced metrics. This glossary breaks down the key terms surrounding Fielding Independent Pitching (FIP), a cornerstone metric for evaluating pitchers on their controllable outcomes, providing a clearer picture of their true talent level.
1.3 True Outcomes
The three batting events that are considered almost entirely under a pitcher's control and not reliant on defense: strikeouts, walks (including hit-by-pitches), and home runs. FIP is built upon these outcomes, as they remove the variable of batted ball luck and defensive skill.
BABIP (Batting Average on Balls In Play)
A statistic measuring a hitter's success rate on batted balls that are not home runs and stay in the field of play. For pitchers, a BABIP significantly higher or lower than the league average (~.300) often indicates luck or poor defense, factors that FIP intentionally excludes.
DIPS (Defense Independent Pitching Statistics)
A theory positing that a pitcher has little control over what happens to a batted ball once it is put in play. Developed by Voros McCracken, this concept is the foundational principle behind metrics like FIP, shifting the focus to outcomes a pitcher directly influences.
ERA (Earned Run Average)
The traditional measure of a pitcher's effectiveness, calculated as the average number of earned runs allowed per nine innings pitched. While useful, ERA can be heavily influenced by factors outside the pitcher's control, such as defensive errors, ballpark factors, and sequencing luck.
Expected ERA (xERA)
A Statcast metric that estimates what a pitcher's ERA should be based on the quality of contact allowed (exit velocity and launch angle), rather than the actual results. It provides another layer of defense-independent evaluation, complementing FIP.
FIP (Fielding Independent Pitching)
The core metric of this glossary. FIP estimates what a pitcher's ERA would look like over a given period, assuming league-average results on balls in play and league-average timing. It is calculated using only home runs, walks, hit-by-pitches, and strikeouts, offering a "purified" view of a pitcher's performance.
FIP Constant
A scaling factor added to the FIP calculation to ensure that, across the entire league, the average FIP aligns with the average ERA for a given season. This allows FIP to be presented on the same scale as ERA for intuitive comparison.
FIP- (FIP Minus)
An adjusted version of FIP where 100 represents the league average, and each point below 100 is one percentage point better than average. A FIP- of 85 for Kevin Gausman, for example, means his FIP was 15% better than the league average, providing easy cross-era and cross-season comparison.
Home Run (HR)
A batted ball that results in the batter circling all bases and scoring a run without the benefit of a fielding error. As one of the "3 True Outcomes," home runs carry significant weight in the FIP formula, as they are entirely the pitcher's responsibility.
Infield Fly Ball
A batted ball hit high in the air within the infield that is almost always caught for an out. These plays are so routine they are excluded from BABIP calculations and are considered a pitcher skill, though they are not a direct component of FIP.
League Average
A central benchmark in sabermetrics. For FIP and related stats, league-average performance provides the baseline (often an ERA or FIP around 4.00-4.50) against which all pitchers, from Blue Jays aces to back-end starters, are measured.
Linear Weights
A system that assigns run values to every possible offensive event (single, double, out, etc.). The FIP formula uses a specific set of linear weights for home runs, walks, and strikeouts to quantify their impact on run prevention.
Luck-Neutral
A descriptor for statistics like FIP that aim to remove the effects of random variation, such as a bloop single falling in or a line drive being caught. The goal is to reveal the underlying skill of the pitcher, which is more predictive of future performance.
Pitcher WAR (Wins Above Replacement)
A comprehensive metric estimating a player's total contribution in wins compared to a readily available replacement-level player. Two common versions are fWAR (Fangraphs WAR), which uses FIP as a key input for pitchers, and bWAR (Baseball-Reference WAR), which uses runs allowed.
Regression to the Mean
The statistical tendency for extreme performances (e.g., an unusually low BABIP or strand rate) to move toward the average over time. FIP is often a better predictor of future ERA because it assumes this regression in areas outside a pitcher's direct control.
SIERA (Skill-Interactive ERA)
An advanced pitching metric that, like FIP, attempts to measure true pitcher ability. It is more complex than FIP, as it also considers balls in play and differentiates between types of hits (ground balls, fly balls), arguing that pitchers can influence contact quality.
Strand Rate (Left On Base Percentage - LOB%)
The percentage of baserunners a pitcher leaves on base without scoring. While elite pitchers like Jordan Romano can sustain high strand rates, extreme numbers are often unstable and influenced by luck and sequencing, which FIP does not account for.
Strikeout (K)
When a pitcher records three strikes on a batter before the batter puts the ball in play or reaches base. As the most desirable of the "3 True Outcomes," strikeouts are highly valued in FIP, as they completely eliminate the variables of defense and batted ball luck.
Walk (BB)
When a pitcher throws four balls to a batter, awarding the batter first base. Along with hit-by-pitches (HBP), walks are negative events fully controlled by the pitcher and are a key component in the FIP calculation.
xFIP (Expected Fielding Independent Pitching)
A variant of FIP that replaces a pitcher's actual home run total with an expected number based on their fly-ball rate and the league-average home-run-to-fly-ball ratio. It is used to predict whether a pitcher's current HR rate is sustainable or due for regression.
For the Toronto Blue Jays front office, led by GM Ross Atkins, metrics like FIP are crucial tools for player evaluation, from assessing the stable performance of an ace like José Berríos to identifying breakout candidates like Yusei Kikuchi. While traditional stats will always have a place in the story of the game at the Rogers Centre, understanding FIP and its related lexicon provides a deeper, more predictive look at the pitchers tasked with helping the Blue Jays compete in the tough American League East and pursue a World Series championship.
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