I just heard Scott Mitchell explain on ESPN 700 why Utah ran the Duck offense under Fassel. He claimed the reason that they ran it was because they didn’t have sufficient O-linemen (injuries; talent). The idea was to take the O-Line and D-Line out of the play and go 7 on 7.
I always thought it was just a quirky Fassel formation. Didn’t realize it was more strategic than that. Though I don’t remember it being all that successful, just something that the fans would cheer for.