The pass rush wasn't great in 2014, no. But we did take the ball away from teams anyway. That's what really matters. Pressure makes that more likely, but as long as you get the ball away, you're ok.
Backup QBs suck all over the league. The best you ought to hope for is a guy who can come in and not kill you like Cassel did to us against the Giants. When you lose your franchise QB, the defense and the ST need to step up, and ours didn't get it done last season. They were close, but they couldn't get it done.