They will now last two instead of three months. With this, Blizzard wants to prevent stagnation.
According to Overwatch director Jeff Kaplan, who announces the changes in a video, the shorter seasons are more fun and rewarding. Despite the shorter duration, players will roughly be able to score the same number of Competitive Points.
He also announces that the degree to which the Skill Rating drops, decreases. Players with a Diamond rank or higher only have to play five games a week to prevent their rating from falling apart. And if that happens, players lose 25 points instead of 50.
In addition, Blizzard will make Competitive Matches on Control-maps last shorter. Currently, many games continue in Overtime and therefore they take a long time. The winner will be determined in a best of three series, instead of a best of five which is currently the case. Placement matches are also adjusted so players get into games with other players that are about the same level.
Kaplan says that all changes will be closely monitored. Overwatch's sixth competitive season starts on August 31st.