Xgoals
xG Guide · Part 4 · Chapter 27

History of xG

Expected goals did not appear overnight. It grew from hand-written notes in the 1950s to the machine-learning models on TV today.

Timeline

1950sReep notatesmatches by hand1997Pollard & Reep:the first shotmodel2004930 World Cupshots modelled2012Opta introducesits xG2013–2016Bloggers show xGpredicts results2017xG on Match ofthe Day2022Opta andStatsBombupgrade models2024Hudl acquiresStatsBomb2026FBref loses itsxG
1950sReep notates matches by hand1997Pollard & Reep: the first shot model2004930 World Cup shots modelled2012Opta introduces its xG2013–2016Bloggers show xG predicts results2017xG on Match of the Day2022Opta and StatsBomb upgrade models2024Hudl acquires StatsBomb2026FBref loses its xG
Expected goals, from hand notation to machine learning.
  1. 1950s

    Charles Reep notates matches by hand and studies how goals come about: early football analytics.

  2. 1997

    Pollard and Reep publish a logistic model of shot success from location, angle and body part: the idea behind xG.

  3. 2004

    Ensum, Pollard and Taylor model 930 shots from the 2002 World Cup.

  4. 2012

    Opta credits Sam Green with introducing its expected goals; in ice hockey the same term spreads at the same time.

  5. 2013–2016

    Bloggers and independent analysts (11tegen11 and others) show xG predicts future results better than goals do.

  6. 2017

    BBC's Match of the Day starts showing xG for the 2017-18 season; xG reaches a mass audience.

  7. 2022

    Opta revamps its model (keeper position, pressure, shot clarity) and drops the big-chance tag; StatsBomb upgrades its own.

  8. 2024

    Hudl acquires StatsBomb; the brand becomes Hudl StatsBomb.

  9. 2026

    FBref loses all its advanced data, xG included, when Opta's feed ends; providers keep refining their models.

Why it caught on

Goals are rare, so results hide a lot of chance. xG gave fans and clubs a way to look past the scoreline: how good were the chances, really? Once TV showed it, the term entered everyday football talk, along with its misreadings.

Questions

Who invented xG?

The idea grew from academic work (Pollard and Reep, 1997) and earlier hand notation by Charles Reep; Opta credits Sam Green with introducing its xG in 2012.

When did xG appear on TV?

BBC's Match of the Day began showing xG in the 2017-18 season.

Sources

  1. Bajons & Kook: expected goals models (arXiv) · 2025
  2. Ensum, Pollard & Taylor: shots at the 2002 World Cup (described in Bajons & Kook) · 2004
  3. Opta Analyst: What is expected goals (xG)? · 2023
  4. American Soccer Analysis: is xG the best predictor of future results? · July 2022
  5. StatsBomb: xG is on TV, now what? · August 2017
  6. Opta Analyst: Evolving expected goals (the 2022 model) · April 2022
  7. Hudl StatsBomb: Upgrading expected goals · May 2022
  8. Sports-Reference blog: FBref

Checked 2026-10-28. Methods change: every figure here is dated to its source.

xG explains football; it is not a betting tip. 18+ · Please gamble responsibly.