Dylan Guenther and Sean Durzi also scored for the Mammoth (30-23-4), who have won two straight games and are 8-1-1 in their past 10 home games. Karel Vejmelka made 29 saves.
Dylan Larkin scored, and John Gibson made 21 saves for the Red Wings (33-19-6), who have lost four of five.
Durzi gave Utah a 1-0 lead 57 seconds into the first period, picking up a loose puck on the end boards and beating Gibson on the blocker side.
Schmaltz scored on a 5-on-3 power play to extend it to 2-0 at 8:11, beating Gibson glove side with a wrist shot.
Guenther pushed it to 3-0 at 4:40 of the third period, slotting the puck between the legs of Gibson.
Larkin scored during a 6-on-4 at 15:52 to cut it to 3-1 with Gibson pulled for the extra skater on the power play. Larkin found a loose puck at the top of the crease after a shot from Moritz Seider and fired it past Vejmelka.
Keller then scored an empty-net goal at 17:42 for the 4-1 final.
