The sectional was slated to start Monday but was pushed back three days due to rain.
"It was originally supposed to be one game a day," said WHS coach Jeremy Hedinger.
Donald Smith cracked a three-run homer and Dakota Bailey followed with a solo shot as Westside grabbed a 4-0 lead in the first inning.
"We've been hitting the ball hard," Hedinger commented. "Those four runs gave us a cushion right from the start."
Independence got within 5-3, but Robertson closed the door after that.
The Patriots put two runners on with one out in the sixth, but Robertson fanned the next two batters.
He retired the side in order in the seventh.
"The defense plays with confidence behind him," Hedinger remarked.
Bailey, Tyler Copley and Thomas Forren each had RBI hits in the third to add to the Renegades lead.
WHS (17-12) took on Liberty in the night cap.
The Thursday losers of the first two games meet Friday to start the action.