Saint Mary's connected on seven 3-pointers in the first half to stay close, trailing by two, 41-39, at halftime. But the Gaels were blanked from distance in the second half.
Meanwhile the Broncos shot a crisp 58.8 percent in the game, connecting on 30 of 51 attempts from the field, draining 6 of 14 from three-point range and adding 16 of 19 from the line.
Brad Waldow scored 29 points and grabbed 11 rebounds to lead Saint Mary's, shooting 9 of 22 from the field and a perfect 11 for 11 from the free throw line.
The Gaels were 25 of 63 from the field (39.7 percent) and finished the game 7 for 24 from distance.