McNichols added a 19-yard TD carry in the fourth as the Broncos (8-4, 5-3 Mountain West) turned a one-score game into an easy win. McNichols finished with 192 yards - a career high and seventh-straight 100-yard day. He also had six receptions for 40 yards and a touchdown.
But Boise State used a 14-play, 97-yard drive that took up 6:41 of the third quarter - culminating in Brett Rypien's 5-yard toss to McNichols - to take the lead for good. Rypien finished 25 of 33 for 197 yards and two touchdown passes.
Potter was 28 of 41 for 336 yards and three touchdowns for the Spartans, but was intercepted twice.