Their #2 tight end is out for a month or two. Doesn't sound like much but they run a LOT of 2 tight end sets. If Kittle goes down they're screwed. They lost a DT and a WR that were in the two deeps also but they didn't start.
I'm guessing Ferentz will risk at least a couple of them and their health to try to win their big rivalry game in a couple of weeks