Based on the UC admit rate I posted which is the average, just based on GPA, your chances were 50/50. Each UC campus will review applicants based on their own criteria, so one decision from one UC campus will not predict your decisions at other campuses. Only UCD can tell you why you did not get in. CS is just so competitive at all schools there are no guarantees.
What kind of EC’s did you have? How were your essays? These are all important components of the application.