In Matt Barrows' post about Jim Harbaugh's conference call earlier today, Barrows reported that sources indicated Michael Crabtree fractured his foot during a June 6 practice and actually had surgery on it prior to training camp. It doesn't indicate how long before training camp, but that would explain the extended absence.
During the call, Harbaugh indicated Crabtree was getting closer to returning. Ideally he'll be good to go in time for the opener. He seems up to speed in the class room, but now it's a matter of converting it to progress on the field. A tandem of Braylon Edwards and Michael Crabtree could be pretty filthy for opposing defenses to deal with on a regular basis. Of course, if the offensive line can't create time I suppose it doesn't really matter.
The return of Crabtree could provide a weapon to counteract the overwhelming blitzes. A few quick slants to Crabtree where he can pick up some YAC might quiet down the blitzing. For now, teams are going to blitz the 49ers like nobody's business until the team proves it can handle it. Whether that means more slants or some screens or some other plan, the team has to figure out a way to get plays off before all hell breaks loose.