I don't know how serious Fum is hurt, but I'd think coaches sat him because he's needed at NU. When Horni looks to pass at 3rd and long, more often than not he targets Fum. He's our chain mover.
Honestly though, I'm not really worried about Wisconsin's pass catching. Other guys, Cephus/Taylors/Peavy, are capable receivers.
The key, as always, is how our offensive line plays. When they execute, we can get the running game going. When the running game is good, we do our things, that is, pass-action passes and what not. When they have holdings and other hiccups, our offense stalls. It's all about those fatties.