"I don't think we played our best basketball most of the time we were in the bubble. The way we ended our season really disappointed me," Ballmer said Wednesday, per Mark Medina of USA Today. "My personality is all about winning."
The Clippers were eliminated in the second round of the playoffs after blowing a 3-1 lead against the Denver Nuggets.
Rivers was fired after the season and was replaced by Tyronn Lue, who was an assistant for the team during the 2019-20 campaign.
Lue had previously won a championship with the Cleveland Cavaliers, reaching the NBA finals in three straight seasons.
Ballmer will hope Lue's experience and a change in approach will be enough for the Clippers to meet expectations in 2020-21.
Los Angeles was considered one of the favorites to win the NBA title this season after adding Paul George and reigning NBA finals MVP Kawhi Leonard last summer. The team was up and down during the regular season but still managed to secure the No. 2 seed in the Western Conference.
However, things didn't click in the postseason, when the Clippers needed six games to get by Luka Doncic and the Dallas Mavericks in the first round before falling to the Nuggets in the conference semifinals.
There are still high expectations going into next year, and the Clippers franchise will be looking to reach its first conference finals while Leonard and George are on the same page.