Benzinger finished with 12 points, including three 3-pointers.
Detroit (9-8, 3-3) led 66-64 with seven minutes left, but Alstork scored nine in a row during a 13-3 run that pulled the Raiders within two about 3 1/2 minutes later.
Benzinger converted a 3-point play and, after a Detroit turnover, Alstork made a layup to tie it at 74-all with 1:08 remaining.
Thomasson missed a 3, but grabbed the rebound and found Benzinger for the winner.
Bass, who tied a career-high with 28 points, missed a potential winning 3 with four seconds left.