On June 8, the Public Policy Institute issued an analysis of California’s June 5 primary. Here is a news story which summarizes the Report, and has a link to the Report itself.
The article is slightly misleading when it says that four incumbents did not place first in their race. Those four incumbents were all running against another incumbent. There were some races which pitted two incumbents against each other, due to redistricting. In all races, incumbents polled the most votes, except when they were running against another incumbent; in those four instances, the two incumbents placed first and second. California had 154 partisan offices up for election.