Oh it was definitely felt when Hill and Williams went down (btw Williams wasn't lost to injury this year). And you're talking about 2 guys. He suggested BYU lead the nation the last few years. I doubt that. Like I said, just felt more when they go down.
Oregon has lost a bunch the last few years. Arkansas this year has lost their top 3 receivers, star RB, starting LB... so far. GT and TN, have like 7 guys out for season. Illinois, Maryland, with like 8. etc, etc. All of these are just out for season, not including injuries that guys will come back from. BYU does have quite a few of those. But I doubt it's the most.
I'm just saying there's no denying it is very noticeable when BYU has injuries. You can't argue that it wasn't extremely noticeable when Hill and Williams went down.