The UCs have officially announced the number of applications for Fall 2018, but not the number of acceptances. So the acceptance rates are not known (at least not officially). I think last year’s rates weren’t officially announced until July. However, based on last year’s data, a 28.5% acceptance rate at UCI seems unlikely.
For Fall 2017, UCI got 85,097 applications. They accepted 31,103, for an acceptance rate of 36.6%.
For Fall 2018, UCI got 94,866 applications. To my knowledge, UCI’s capacity hasn’t changed significantly over the past year. So they will probably accept about the same number of applicants that they did last year. In that case, the acceptance rate would be around 33%.
For Fall 2017, USCB got 81,828 applications. They accepted 26,879, for an acceptance rate of 32.8%.
For Fall 2018, UCSB got 92,017 applications. Again, let’s assume that they accept about the same number as last year. In that case, the acceptance rate would be around 29%.
https://www.ucop.edu/institutional-research-academic-planning/_files/factsheets/2017/fall-2017-admissions-table2.pdf
https://www.ucop.edu/institutional-research-academic-planning/_files/factsheets/2018/fall-2018-applications-table1.pdf