4 wins was the best season Utah State had in that stretch. They were a cupcake win padder. Of course, BYU was one of the 4 wins in the 2010 season, so maybe not that year.
Bronco also lost twice to 5 win Utah teams. Even when BYU was clearly better during the streak, Utah got up for the game.
Boise was obviously added late in Bronco's tenure splitting the 4 games.