South Mountain broke a 2-2 tie with an eight-run explosion in the second inning, thanks in large part to three Hancock errors and RBI doubles by Reed Cantler and Casey Strunk.
South Mountain scored three more in the third on a two-run single by James Merson and another RBI single by Conner McLellan to increase its lead to 13-4.
"Like I've said before, we give them a lot of runs, and tonight we did a lot of that," said Kerns.
Hancock came into the game looking listless. South Mountain starter Travis Stone held Hancock's bats mostly in check, giving up only three earned runs in 3 1/3 innings.
But reliever Trevor Walsh gave up five runs in one inning, including an RBI single to Brayden Litton and a two-run single to Ryan Smith, which cut the deficit to 15-9.
"Travis was fantastic, though we may have fooled ourselves putting him back into the game," said South Mountain coach Joe Schofield.
After two straight Tyler Hollis walks to start the bottom of the sixth inning, Stone retook the mound, but by that time fatigue had set in.
Hancock manufactured nine runs on seven hits, including a two-run single by Brayden Litton and a two-run double by Conner Litton, who led Hancock with six RBIs.
"It's good, it's definitely good," Conner Litton said of the win, "It keeps us going on to the championship."
Conner Litton also shined in relief, allowing two hits in two innings to shut the door on South Mountain's season.
"My team has what it takes to play with anybody, but they coasted. It's a seven-inning game," said Schofield. "We couldn't finish the deal."