You are talking apples and oranges.
Of the kids that do transfer, they do well as the link you gave said. However most never transfer.
With 11 million students, community colleges are home to 45 percent of the collegiate population in the United States. The report found 81.4 percent of students who enter community colleges for the first time planned to obtain a bachelor’s degree in the future, but just 11.6 percent achieved that goal.
Community College Students Often Fail To Achieve Bachelor's Degree: Study | HuffPost College
The system’s transfer rate isn’t good. Only 23 percent of California’s degree-seeking community college students transfer within six years, according to the Campaign for College Opportunity.
https://www.insidehighered.com/news/2013/08/08/californias-two-year-colleges-roll-out-transfer-degrees-while-lawmakers-consider
The UC graduation rate for kids entering as frosh is 83% according to http://accountability.universityofcalifornia.edu/index/chapter/4
If only 23% of CC kids transfer to a 4-year college (and not all of them graduate) the numbers are not remarkably similar.