The North American League Championship Series will be changing its regular season format starting with the 2016 Summer Split, League of Legends developer Riot Games announced in a statement. Instead of single-game matchups between opponents, weekly matches will take place over a best-of-3 series. The European LCS will be switching to a best-of-2 format.
The NA LCS weekends will be extended to three days as a result, running from Friday through Sunday. On Saturday and Sunday, multiple games will be played concurrently with multiple streams to give viewers the option of which matchup they would like to watch. The EU weekends will take place over two days with concurrent streams.
Examples, from Riot:
Riot's explanation, from the release:
For many of us, Bo1s don't feel as satisfying as a longer series - due to their short nature, there's not as strong a feeling of victory when a team wins as there would be with a more extended series. Teams currently don't get a lot of practice in a competitive best-of series which may affect their ability to adapt mid-series in the LCS post-season and the knockout stages of MSI and Worlds. Beyond this, the Bo1 format means more time between games because more teams are transitioning to and from the stage - we'd generally like to decrease time between games in 2016.
Bo3s provide a lot of competitive benefits, including rigorous competition between teams due to the sheer number of games. In common with Bo1s, it's also emotionally satisfying to watch as a fan since there's a clear winner at the end of every series. A drawback is that each matchup between teams may seem less fair because of the number of games on each side and total number of games played. Like Bo2s, Bo3s could also offer less popular and/or low interest matchups for an extended time.
The NA LCS and EU LCS will have different formats due to cultural reasons, Riot explained in the release. Best-of-2 series in European soccer tournaments are not uncommon, while American sports are quite averse to ties.