BYU O-line have approximately 50 D1 snaps combined. One or two guys get banged up at the same time and it can be a huge drop off.
Same with D-line, Nelson is solid, Mangleson has experience but it's at DE not inside. Latu and Singh have about 100 combined snaps at D1 and the results were under average last season. The other DTs are JC players with no D1 snaps and freshmen. Same as the O-line if a player or two get banged up, it's probably a big drop off.
RBs have some injury concerns, Ropati and Davis have been injured more than they've been healthy over the last 3 seasons. Martin was banged up last season off and on, plus he's coming off injury to start the season. Behind them it's freshmen.
I can see BYU starting hot like last season while most are healthy and having Arizona State and Houston for the last two games gives me confidence they can get 5 or 6 even with some injuries. SMU not looking very good against Nevada gives me some more confidence they can get to at least 5.
I have $100 on the over for BYU. I originally had $250 on the over in July but I feel a little less confident than I did then due to depth, especially in the trenches.