West Deptford (4-3, 3-1) squandered some early chances, as the Eagles had five baserunners in the first two innings.
"We have to take advantage of our opportunities," West Deptford coach John Oehler said. "We let them get out ahead of us, and that changed the game."
Sterling scored four runs in the first. Ryan McGoldrick led off with a double, and Mazzone rapped a two-run single. Two other runs scored on errors.
Harding, the team's No. 9 hitter, drove a pitch over the left-field fence to give the home team a 6-0 lead in the third.
"We needed a win in a big way," said Sterling coach Chris Hoffman, whose team suffered its first defeat Tuesday, 5-4 to Woodbury. "That loss was a wake-up call."
Unlike most pitchers, Casey works backward: He uses his change-up and curve to set up his fastball.
He said his change-up has been his best pitch since he discovered a new grip in the spring of his freshman year.
"I must have tried five or six different grips, and none of them were working for me," Casey said. "Now I throw kind of a circle change. I found the grip, and I was like, 'Wow, it works for me. The ball drops off the table.' "
Casey escaped first-inning trouble with a strikeout and pickoff. He worked out of a bases-loaded, one-out jam with two strikeouts in the second.
Those two strikeouts began a run of 16 consecutive retired batters. He struck out six in the stretch but also got eight groundouts and two pop-outs.
West Deptford 000 000 0 - 0 4 3
Sterling 402 100 x - 7 9 0
WP: Donovan Casey. LP: Ty Castellano. 2B: S-Ryan McGoldrick. HR: S-J.T. Harding.
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