Ever seen a window pop up called “win probability” when watching LoL games? Riot Games shared important info on how it’s calculated at Worlds 2023.

Image Credit: Riot Games

LoL Win Probability Explained

John “Riot JPham” Pham, product lead for Win Probability (WP), gave some important insights for the most avid LoL Esports fans. Not only is WP returning for Worlds after the positive feedback from MSI (it was previously called Win Expectancy), but we’re getting the chance to better understand how it really works.

What Is Win Probability (WP)?

According to the Rioter, WP is a machine learning-based tool that indicates how often teams won given a similar situation previously.

In LoL’s case, WP is calculated as a percentage by by comparing the current game situation to similar historical situations using key considerations such as the side (red vs blue), game time, gold differences in real-time, and other in-game metrics.

The percentage comes from the number of teams that faced a comparable situation in the past and went on to win the game. For Riot, the stat is developed using a machine learning algorithm called xgboost.

Read more: LoL Worlds 2023 – Results, standings, and more

How WP Works at Worlds 2023

There are many different factors that the WP machine learning model takes into consideration to get the stat. In particular, the current version of the model is trained using all professional LoL Esports games since patch 10.4. It accounts for changes over time as it incorporates new game results into the training set, allowing it to factor in meta shifts and game changes.

Below are the list of factors WP takes into account:

Game time (in-game time)
Gold percentage (player gold relative to total game gold)
Total team XP
Number of players alive
Tower kills
Dragon kills (whether a team possesses dragon soul or not)
Herald trinket in inventory
Inhibitor timers (time until an inhibitor respawns) for each inhibitor
Baron timers (time until Baron buff expires for the team)
Elder timer (time until Elder Dragon buff expires for the team)
Number of players with Baron active
Number of players with Elder active

Interpreting Win Probability

Riot gave a clear example of what WP is by taking an example of Game 3 between C9 and BLG from MSI 2023.

Image Credit: Riot Games

The graph displays in-game time on the x-axis and WP percentages on the y-axis, with blue and red teams indicated. The central line is the 50% win expectancy, meaning that teams have even chance for both teams at that point of the game. As the game progresses, slopes above or below the central line depict the WP for each team at specific times.

On the top of the graph, Riot marks the most important objectives or events that can heavily influence WP in those moments.

With that being said, it’s important to note that WP doesn’t predict the game’s outcome, but rather reflects changes in the game-state compared to past performances.

In other words, it should help viewers get a visual idea on how the game is progressing and show how the two teams are behaving relative to the other. It also serves as a tool to help fans and casters appreciate the impact of pivotal moments and decisions in the game.

Related: Worlds 2023 Play-in Match Predictions

The difference between Win Probability and Gold Difference

Before the introduction of WP, Gold Difference (GD) was the primary metric for assessing the game state. That being said, Gold Difference had several limitations, mainly the one being the inability to account for other in-game metrics and the lack of an easily understandable percentage.

With WP, instead, this is no longer the case. It includes more factors and it’s easier to understand and brings more consistency throughout the game, and a better visualization of impactful events.

How Win Probability will evolve in the future

According to the Riot JPham, they are looking to incorporate more data into the model, including things like team composition, micro interactions in team fights, and individual dragon data. “This could lead to the development of Win Probability Added (WPA), quantifying the percentage change in a team’s chances of winning due to specific events,” he said.

Regardless of what they do, the goal is to find ways to give LoL fans more insights, and better represent the state of the games.

Worlds 2023 and AWS join forces

To enhance WP at Worlds, there will be an active collaboration behind the scenes with AWS to refine the WP graphic, improve transparency, and enhance the experience for fans, casters, and the community. WP will be strategically displayed to highlight crucial moments in the game and showcase the influence of key plays.

Final Thoughts

If the WE were implemented last year, fans could’ve gotten a clearer idea of the back-and-forth battle in the grand final between T1 and DRX. The goal of the WP is to highlight those moments and visually showcase those plays in the best way possible and allow fans to appreciate them even more.

Read more: LoL 2023 Worlds Power Rankings