The topics discussed below represent Riot’s policies as they stand right now. Our policies evolve and change as the community and our understanding of it grows. This page will be updated whenever any policies relevant to the API change. Violating any of the policies below can result in revocation of your access to the public API.
ranked VS. NON-RANKED games
From Rioter Matt Enth:
Our intention is that normal games are similar to pickup sports, where you're there for fun and are trying to win, but the stats ultimately don't matter. As a result, normals are friends only. We had an old version of Match History where players could set public, private, or friends only, but ultimately decided against that model here because the implications of setting "normals" to public are unclear. As soon as you set to "public," odds are that your normal win rates would become permanently available. We want ranked to be a legitimate sphere of competition, and we feel that, in order to preserve that legitimacy, stats need to be public. At the very basic level, those stats are "who played which champ" and "what was the outcome of the game." Imagine if Little League baseball just showed relative standings, but no public win/loss record - it'd feel a little sketchy, right? We want to avoid that same feeling. As a result, we've opted for higher transparency.
This quote, by one of the product owners for the match history team, explains the context for Riot’s current position on ranked and non-ranked games. This announcement from when the match history website was first launched provides more information. http://na.leagueoflegends.com/en/news/game-updates/features/announcing-new-match-history-beta
You can see the result of the position we’ve taken in the client, match history website, as well as the API where participant information is not included for non-ranked games. In most cases, it is possible to match up the participants in a match with the champions in their matchlist in an attempt to de-anonymize the data. However, displaying non-ranked matches with the data de-anonymized in this way is against our policies. We ask developers to respect the decision we’ve made around non-ranked games. To be explicit, we don’t mind if you list these non-ranked games as part of a player’s history, but we do ask that, in all cases, the names of the player be excluded from non-ranked game data and only champion names be displayed. You may collect de-anonymized data for non-ranked games, but you may not display it to any players. As always if you think there is an edge case and you’re not sure if your project will come into conflict with our policies, please reach out to us via the messages within your application.
Our position on aggregation of statistics is tied to our position on Ranked vs. Non-Ranked Games. Feel free to dissect a player’s ranked match history to provide players with detailed insights. However we do ask that developers don’t display aggregated statistics for a player’s non-ranked match history to provide win rates, KDA, or other measures of their performance. You may not display personalized aggregated statistics for non-ranked games either independently or collectively with ranked games. Displaying population-wide aggregated stats for non-ranked games is allowed. You may collect personalized aggregated statistics for non-ranked games for future use in case the policy changes later. However, you may not ever display these non-ranked aggregated stats in a way that can be tied to individual players. As always if you think there is an edge case and you’re not sure if your project will come into conflict with our policies, please reach out to us via the messages within your application.