​
​
Sign In
  • Support FanGraphs
    FanGraphs Membership
    FanGraphs Shirts
    FanGraphs Mugs
    Gift a Membership
    Donate to FanGraphs
  • Fantasy
    Fantasy Tools
    Fantasy Player Rater
    Auction Calculator
    Ottoneu Fantasy Baseball
    Signup, FAQ, Blog Posts
  • Blogs
    Blog Roll

    FanGraphs
    • FanGraphs Weekly Mailbag: July 26, 2025
    • Effectively Wild Episode 2353: Wouldn't Trade Him for the World
    • Yankees Patch Their Third Baseman-Shaped Hole With Ryan McMahon
    • Mariners Bolster Lineup by Acquiring Josh Naylor From Diamondbacks
    Podcasts: Effectively Wild

    FanGraphs Prospects

    RotoGraphs
    • 2025 Trade Deadline Fantasy Movers: AL Edition
    • 2025 Trade Deadline Fantasy Movers: NL Edition
    Podcasts: The Sleeper and The Bust | Field of Streams | Beat the Shift

    Community Research
    • Effectively Wild's Preseason Predictions Game Update: Ben Clemens

    Archived Blogs: The Hardball Times | NotGraphs | TechGraphs | FanGraphs+
    Archived THT: THT Live | Dispatch | Fantasy | ShysterBall
    Archived Podcasts: FanGraphs Audio | Chin Music | UMP: The Untitled McDongenhagen Project | Stealing Home | Doing It For Bartolo | OttoGraphs |
  • Projections
    2025 Pre-Season Projections
    ZiPS, ZiPS DC
    Steamer
    Depth Charts
    ATC
    THE BAT, THE BAT X
    OOPSY
    2025 600 PA / 200 IP Projections
    Steamer600, Steamer600 (Update)
    2025 Updated In-Season Projections
    ZiPS (RoS), ZiPS (Update), ZiPS DC (RoS)
    Steamer (RoS), Steamer (Update)
    Depth Charts (RoS)
    ATC DC (RoS)
    THE BAT (RoS), THE BAT X (RoS)
    OOPSY DC (RoS)
    3-Year Projections
    ZiPS 2026, ZiPS 2027
    On-Pace Leaders
    Every Game Played, Games Played %
    Cy Young Award Projections

    Auction Calculator
  • Scores
    Today
    Live Scoreboard, Probable Pitchers
    Live Daily Leaderboards
    Win Probability & Box Scores
    2025, 2024, 2023, 2022, 2021, 2020, 2019
    AL Games
    PHI (4) @ NYY (1)Top 5
    CLE @ KCR14:40
    TOR @ DET18:10
    COL @ BAL19:05
    ATL @ TEX19:05
    ATH @ HOU19:10
    WSN @ MIN19:10
    CHC @ CHW19:10
    CLE @ KCR19:15
    LAD @ BOS19:15
    SEA @ LAA21:35
    NL Games
    ARI @ PIT18:40
    TBR @ CIN18:40
    MIA @ MIL19:10
    SDP @ STL19:15
    NYM @ SFG21:05
  • Standings
    2025 Projected Standings
    2025 Playoff Odds, Playoff Odds Graphs
    2024 ZiPS Postseason Game-By-Game Odds
    AL East
    Blue Jays62420.0
    Yankees56475.5
    Red Sox55507.5
    Rays53519.0
    Orioles455816.5
    AL Central
    Tigers60450.0
    Guardians51517.5
    Twins50539.0
    Royals50539.0
    White Sox386621.5
    AL West
    Astros60440.0
    Mariners55495.0
    Rangers54506.0
    Angels505410.0
    Athletics446217.0
    NL East
    Mets60440.0
    Phillies59440.5
    Marlins495310.0
    Braves445815.0
    Nationals416218.5
    NL Central
    Brewers61420.0
    Cubs60431.0
    Reds54507.5
    Cardinals54518.0
    Pirates426219.5
    NL West
    Dodgers61430.0
    Padres55496.0
    Giants54507.0
    D-backs515310.0
    Rockies277633.5
  • Leaders
    Major League Leaders
    Batting: 2025, 2024, 2023, 2022, 2021, Career
    Pitching: 2025, 2024, 2023, 2022, 2021, Career
    Fielding: 2025, 2024, 2023, 2022, 2021, Career
    Major League Leaders - Rank
    Batting: Ranking Grid, Compare Players, Compare Stats
    Pitching: Ranking Grid, Compare Players, Compare Stats
    Splits Leaderboards
    Pitch-Type Splits Leaderboards
    Season Stat Grid

    Postseason Leaders
    Batting: 2024, (WS), (LCS), (LDS), (WCS), Career
    Pitching: 2024, (WS), (LCS), (LDS), (WCS), Career

    Spring Training Leaders
    Batting: 2025, 2024, 2023
    Pitching: 2025, 2024, 2023

    KBO Leaders
    Batting, Pitching
    NPB Leaders
    Batting, Pitching

    Minor League Leaders
    AAA: International League, Pacific Coast League
    AA: Eastern League, Southern League, Texas League
    A+: Midwest League, South Atlantic League, Northwest League
    A: California League, Carolina League, Florida State League
    CPX: Arizona, Florida
    R: Dominican Summer League
    College Leaders
    Batting, Pitching

    WAR Tools
    Combined WAR Leaderboards
    WAR Graphs
    WPA Tools
    WPA Inquirer
    Rookie Leaders
    Batters 2025, Pitchers 2025
    Splits Leaders
    Batters: vs L, vs R, Home, Away
    Pitchers: vs L, vs R, Home, Away
  • Teams
    Team Batting Stats
    2025, 2024, 2023, 2022, 2021, 2020
    Team Pitching Stats
    2025, 2024, 2023, 2022, 2021, 2020
    Team WAR Totals (RoS)
    AL East
    Blue Jays  |  DC
    Orioles  |  DC
    Rays  |  DC
    Red Sox  |  DC
    Yankees  |  DC
    AL Central
    Guardians  |  DC
    Royals  |  DC
    Tigers  |  DC
    Twins  |  DC
    White Sox  |  DC
    AL West
    Angels  |  DC
    Astros  |  DC
    Athletics  |  DC
    Mariners  |  DC
    Rangers  |  DC
    NL East
    Braves  |  DC
    Marlins  |  DC
    Mets  |  DC
    Nationals  |  DC
    Phillies  |  DC
    NL Central
    Brewers  |  DC
    Cardinals  |  DC
    Cubs  |  DC
    Pirates  |  DC
    Reds  |  DC
    NL West
    D-backs  |  DC
    Dodgers  |  DC
    Giants  |  DC
    Padres  |  DC
    Rockies  |  DC
    Positional Depth Charts
    Batters: C, 1B, 2B, SS, 3B, LF, CF, RF, DH
    Pitchers: SP, RP
  • RosterResource
    Current Depth Charts
    AL East
    Blue Jays
    Orioles
    Rays
    Red Sox
    Yankees
    AL Central
    Guardians
    Royals
    Tigers
    Twins
    White Sox
    AL West
    Angels
    Astros
    Athletics
    Mariners
    Rangers
    NL East
    Braves
    Marlins
    Mets
    Nationals
    Phillies
    NL Central
    Brewers
    Cardinals
    Cubs
    Pirates
    Reds
    NL West
    D-backs
    Dodgers
    Giants
    Padres
    Rockies
    In-Season Tools
    2025 Closer Depth Chart
    2025 Injury Report
    2025 Payroll Pages
    2025 Transaction Tracker
    2025 Schedule Grid
    2025 Probables Grid
    2025 Lineup Tracker
    2025 Minor League Power Rankings
    Offseason Tools
    2025 Free Agent Tracker
    2025 Offseason Tracker
    2025 Opening Day Tracker
  • Prospects
    Prospects Home
    The Board
    The Board: Scouting + Stats!
    How To Use The Board: A Tutorial
    Farm System Rankings

    Top Prospects List
    20252024
    AL
    BALCHWATH
    BOSCLEHOU
    NYYDETLAA
    TBRKCRSEA
    TORMINTEX
    NL
    ATLCHCARI
    MIACINCOL
    NYMMILLAD
    PHIPITSDP
    WSNSTLSFG
    2025 Preseason Top 100
  • Glossary
    Library
    Batting Stats
    wOBA, wRC+, ISO, K% & BB%, more...
    Pitching Stats
    FIP, xFIP, BABIP, K/9 & BB/9, more...
    Defensive Stats
    UZR Primer, DRS, FSR, TZ & TZL, more...
    More
    WAR, UBR Primer, WPA, LI, Clutch
    Guts!
    Seasonal Constants
    Park Factors
    Park Factors by Handedness
  • Sign In
  • Intro
  • Features
  • Offense
    • Complete List (Offense)
    • OBP
    • OPS and OPS+
    • wOBA
    • wRC and wRC+
    • wRAA
    • Off
    • BsR
    • UBR
    • wSB
    • wGDP
    • BABIP
    • ISO
    • HR/FB
    • Spd
    • Pull%/Cent%/Oppo%
    • Soft%/Med%/Hard%
    • GB%, LD%, FB%
    • K% and BB%
    • Plate Discipline (O-Swing%, Z-Swing%, etc.)
    • Pitch Type Linear Weights
    • Pace
  • Defense
    • Overview
    • Def
    • UZR
    • DRS
    • Defensive Runs Saved – 2020 Update
    • Inside Edge Fielding
    • Catcher Defense
    • FSR
    • RZR
    • TZ / TZL
  • Pitching
    • Complete List (Pitching)
    • PitchingBot Pitch Modeling Primer
    • Stuff+, Location+, and Pitching+ Primer
    • ERA
    • WHIP
    • FIP
    • xFIP
    • SIERA
    • Strikeout and Walk Rates
    • Pull%/Cent%/Oppo%
    • Soft%/Med%/Hard%
    • GB%, LD%, FB%
    • BABIP
    • HR/FB
    • LOB%
    • Pitch Type Linear Weights
    • SD / MD
    • ERA- / FIP- / xFIP-
    • Plate Discipline (O-Swing%, Z-Swing%, etc.)
    • Pace
    • PITCHF/x
      • What is PITCHF/x?
      • Pitch Type Abbreviations & Classifications
      • Heat Maps
      • Common Mistakes
      • PITCHf/x Resources
  • WE/RE/LI
    • RE24
    • Win Expectancy
    • WPA
    • LI
    • WPA/LI
    • Clutch
  • Principles
    • DIPS
    • Regression toward the Mean
    • Replacement Level
    • Sample Size
    • Splits
    • Projection Systems
    • Linear Weights
    • Counting vs. Rate Statistics
    • Park Factors
    • Park Factors – 5 Year Regressed
    • Positional Adjustment
    • Aging Curve
    • League Equivalencies
    • Pythagorean Win-Loss
    • Luck
  • WAR
    • What is WAR?
    • WAR for Position Players
    • WAR for Pitchers
    • FDP
    • fWAR, rWAR, and WARP
    • WAR Misconceptions
  • Business

SIERA

by Piper Slowinski
July 27, 2011

Skill-Interactive ERA (SIERA) is the newest in a long line of ERA estimators. Like it’s predecessors FIP and xFIP, SIERA attempts to answer the question: what is the underlying skill level of this pitcher? How well did they actually pitch over the past year? Should their ERA have been higher, lower, or was it about right?

But while FIP and xFIP largely ignore balls in play — they focus on strikeouts, walks, and homeruns instead — SIERA adds in complexity in an attempt to more accurately model what makes a pitcher successful. SIERA doesn’t ignore balls in play, but attempts to explain why certain pitchers are more successful at limiting hits and preventing runs. This is the strength of SIERA; while it is only slightly more predictive than xFIP, SIERA tells us more about the how and why of pitching.

Here’s what SIERA tells us:

Strikeouts are good…even better than FIP suggests. High strikeout pitchers generate weaker contact, which means they allow fewer hits (AKA have lower BABIPs) and have lower homerun rates. The same can be said of relievers, as they enter the game for a short period of time and pitch with more intensity.

Also, high strikeout pitchers can increase their groundball rate in double play situations. Situational pitching is a skill for pitchers with dominant stuff.

Walks are bad…but not that bad if you don’t allow many of them. Walks don’t hurt low-walk pitcher nearly as much as they hurt other pitchers, since low-walk pitchers can limit further baserunners. Similarly, if a pitcher allows a large amount of baserunners, they are more likely to allow a high percentage of those baserunners to score.

Balls in play are complicated. In general, groundballs go for hits more often than flyballs (although they don’t result in extra base hits as often). But the higher a pitcher’s groundball rate, the easier it is for their defense to turn those ground balls into outs. In other words, a pitcher with a 55% groundball rate will have a lower BABIP on grounders than a pitcher with a 45% groundball rate. And if a pitcher walks a large number of batters and also has a high groundball rate, their double-play rate will be higher as well.

As for flyballs, pitchers with a high flyball rate will have a lower Homerun Per Flyball rate than other pitchers.

Finally we have a stat that A) is accurate and predictive, and B) accounts for some of the complexity of pitching.

Context:

SIERA is on a similar scale to ERA, so any score that is a good ERA is also a good SIERA. Please note that the following chart is meant as an estimate, and that league-average SIERA varies on a year-by-year basis. To see the league-average ERA for every year from 2002 to the present, check the FanGraphs leaderboards.

Rating SIERA
Excellent 2.90
Great 3.25
Above Average 3.75
Average 3.90
Below Average 4.20
Poor 4.50
Awful 5.00

In general, relief pitchers have lower SIERA scores than starting pitchers. As a handy shortcut, a pitcher that switches from starting to the bullpen will on average see their SIERA drop by 0.37 points (and vice versa).

Things To Remember:

● Interested in calculating SIERA yourself? Good luck. But if you want to try, here’s Matt Swartz’s formula and explanation.

● As always, when evaluating pitchers, it’s best to use multiple statistics instead of relying on one alone. While  SIERA is the most accurate of the ERA-estimators, it’s only slightly more accurate than xFIP. Both xFIP and FIP still have their uses, so I wouldn’t recommend ditching them entirely and using only SIERA — a balanced approach is always best. You can learn a lot about a pitcher by looking at which metrics like and dislike them, and for what reasons.

● In and of itself, SIERA works as well as many projection systems in terms of predicting a player’s future ERA. But be careful of this distinction: SIERA is technically a backward-looking ERA estimator and not a forward-looking projection system. If you want to turn SIERA from an estimator and into a projection, you can follow the general formula laid out by Matt Swartz in this piece.

● SIERA is park-adjusted, meaning it adjusts for the fact that some pitchers play in PETCO Park and others in Yankee Stadium.

●SIERA is updated for the new (low-scoring) run environment around the majors.

Links for Further Reading:

SIERA Primer, Part One: Introduction — FanGraphs

SIERA Primer, Part Two: Underrated Pitching Skills — FanGraphs

SIERA Primer, Part Three: Differences Between xFIP — FanGraphs

SIERA Primer, Part Four: Testing — FanGraphs

SIERA Primer, Part Five: What Didn’t Work — FanGraphs




ERA- / FIP- / xFIP-
 
Plate Discipline (O-Swing%, Z-Swing%, etc.)

Piper was the editor-in-chief of DRaysBay and the keeper of the FanGraphs Library.

Subscribe
Login
Notify of
Please login to comment
4 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
joram njoroge
13 years ago

send for me the program

-3
KWS
13 years ago
Reply to  joram njoroge

Someone has set us up the bomb

-2
Mike
13 years ago

Can you use the FIP figures and compare for pitching match-ups to make money betting?

-5
nichove
12 years ago

Does anybody know where to get 2010 siera projections?

-5
    FanGraphs Weekly Mailbag: July 26, 2025
    7/26 – Matt Martell
     
    9
    Effectively Wild Episode 2353: Wouldn't Trade Him for the World
    7/26 – Ben Lindbergh
    Yankees Patch Their Third Baseman-Shaped Hole With Ryan McMahon
    7/25 – Davy Andrews
     
    25
    Mariners Bolster Lineup by Acquiring Josh Naylor From Diamondbacks
    7/25 – Dan Szymborski
     
    22
    Nick Allen and the Meritocratic Tyranny of the Batting Order
    7/25 – Davy Andrews
     
    3
    José Soriano Can Get You to Whiff, but He Won’t Strike You Out
    7/25 – Jake Mailhot
     
    2
    Eric Longenhagen Prospects Chat: 7/25/25
    7/25 – Eric Longenhagen
     
    1
    Tyler Mahle Addresses His 2018 FanGraphs Scouting Report
    7/25 – David Laurila
     
    1
    Can I Interest You in a Lightly Used Oriole?
    7/25 – Michael Baumann
     
    14
    2025 Trade Value Series Chat
    7/25 – Ben Clemens
     
    3
    2025 Trade Value: Nos. 1-10
    7/25 – Ben Clemens
     
    262
    Effectively Wild Episode 2352: Turn Every Paige
    7/25 – Ben Lindbergh
You are going to send email to

Move Comment

Updated: Thursday, July 24, 2025 6:00 AM ETUpdated: 7/24/2025 6:00 AM ET
@fangraphs - Contact Us - Advertise - Terms of Service - Privacy Policy
sis_logo
All major league baseball data including pitch type, velocity, batted ball location, and play-by-play data provided by Sports Info Solutions.
mlb logo
Major League and Minor League Baseball data provided by Major League Baseball.
Mitchel Lichtman
All UZR (ultimate zone rating) calculations are provided courtesy of Mitchel Lichtman.
TangoTiger.com
All Win Expectancy, Leverage Index, Run Expectancy, and Fans Scouting Report data licenced from TangoTiger.com
Retrosheet.org
Play-by-play data prior to 2002 was obtained free of charge from and is copyrighted by Retrosheet.