Scarpetta (2-2) allowed only a two-out single in the first to Giants' first-round pick Buster Posey and a walk, retiring 11 consecutive batters from the first through the fifth. He recorded seven strikeouts in one eight-batter span.
The 20-year-old right-hander pitched in 12 Rookie-level games, making eight starts, between the Arizona League Brewers and Helena of the Pioneer League this season, going 2-0 with a 2.23 ERA.
Hankerd staked Scarpetta to a quick lead when he emptied the bases in the opening frame. Fellow Diamondbacks prospect Mark Hallberg started the inning with a single, James Skelton (Tigers) walked and Miles Durham (Pirates) singled before Hankerd connected for his fifth Hawaii Winter Baseball homer.
Hankerd is hitting .368 (14-for-38) with 10 runs scored and 18 of his league-leading 30 RBIs over the last 11 games.
Orioles Minor Leaguer Tyler Henson stroked a two-run single in the second en route to his fourth straight multi-hit game for West Oahu (17-14), which nailed down a spot in Sunday's Championship Game.
Hallberg was 3-for-5 and scored twice to raise his average to .352 over 31 contests.
Waikiki starter Mitsuo Yoshikawa (3-2) surrendered six runs on seven hits and four walks with three strikeouts in three innings.
Yonder Alonso had three hits, while fellow Reds prospect Todd Frazier and Yankees Minor Leaguer Damon Sublett each drove in a run for the BeachBoys (17-16), who remained a half-game in front of Honolulu in the HWB East.
Steve Conley is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.