The Stars (23-26) fell six games behind San Rafael in the North American Baseball League, and Hawaii will be eliminated from playoff contention with another loss or one more win by the Pacifics, who finish their season by hosting Maui in another six-game set.
Gered Mochizuki was 2-for-3 with a triple and two RBIs for Maui (30-25), which moved to within two games of first place. Valdez scored four runs to go along with his four RBIs.
Loeffler (6-3) allowed eight runs — five earned — and seven hits with three walks in five innings.
Hawaii outhit Maui 15-10 but left 11 runners on base. Adam Jacobs was 3-for-4, and Dion Pouncil, Matt Hibbert and Reece Alnas each had two hits apiece.
Chad Blackwell (8-1) scattered 10 hits in seven innings, yielding two runs with six strikeouts.