Paul Watson supplied 14 points and Cezar Guerrero added 13 points for the Bulldogs (21-17), who took a commanding 43-24 cushion into the break after shooting a blistering 76.2 percent (16-of-21) from the floor. They were 6- of-10 from beyond the arc.
Brett Bisping tallied 20 points to lead Siena (19-18).
The Saints rallied from 12 points down in the second half to beat the Bulldogs in Game 1, 61-57, in Fresno on Monday night. They did not allow a field goal over the final 6:59.
Siena will also host the do-or-die Game 3 on Saturday. In the CBI's previous six championship series, the winner of the opening game went on to win the title.
Fresno State cruised to the easy win over the final 20 minutes.