Bennedict Mathurin, Pelle Larsson and Justin Kier each scored 13 points. Kier, the team's only senior, made his first start of the season for the Wildcats (28-3, 18-2 Pac-12), who finished 17-0 at McKale Center and solidified a potential #1 seed in the NCAA Tournament.
Cal (12-19, 5-15) got 16 points from Jordan Shepherd. Makale Foreman contributed 12 points and Lars Thiemann scored 11 as the Bears played without starting point guard Joel Brown because of a knee injury.
Ballo made all seven of his shots from the field and grabbed five rebounds in 17 minutes.
Arizona coach Tommy Lloyd, whose team was playing its fifth game in 10 days, expanded his eight-man rotation by one — giving quality minutes to freshman Adama Bal. He then pulled all but one of his starters with 6:16 left and the Wildcats up 72-53. Bal scored a career-high seven points in 17 minutes.
Arizona led 40-31 at halftime and steadily pulled away, shooting 62.5 percent from the field (30 of 48) and making 23 of 31 attempts from the free throw line.
Mathurin grabbed the ball off the opening tip and dunked three seconds into the game, but Arizona didn't make another basket until Larsson's dunk and free throw at the 14:34 mark gave Arizona a 7-4 lead.
After that, it was all Ballo for a while. The backup big man scored 11 points, including three dunks off nifty interior passes, in a span of 3:08. His layup with 9:42 to go capped a 10-0 run that put the Wildcats up 26-9.
Cal chipped away late in the half, holding the Wildcats without a field goal for the final 3:52, climbing within nine points at the break.