Siakam, who is averaging 24.5 points in four games, scored less than 23 for the first time this season. The 6-foot-9 sophomore's 16 rebounds were one off a career best.
Eli Chuha added 15 points and nine rebounds for the Aggies (3-1), who shot 10 of 24 from 3-point range. Braxton Huggins made 4 of 6 3-point attempts and Ian Baker was 3 of 8. Both finished with 12 points.
The Delta Devils (0-3) struggled from the field at 26 percent. Rashaan Surles, who shot 4 of 14 for nine points, was the only Mississippi Valley State player to make more than two field goals.