One of the biggest hopes of the 49ers entering training camp was that somebody would emerge from among the wide receiver corps to take the place of the injured Michael Crabtree.After a week in camp, however, things haven't gone as planned.Injuries have taken their toll, and some prospects haven't yet taken advantage of the opportunity.A.J. Jenkins, the team's top draft pick from 2012, suffered a minor hamstring injury Tuesday and wasn't able to practice, as did another receiver, Kassim Osgood. Veteran Kyle Williams also has been sidelined this week by a sore hamstring. Rookie Quinton Patton has an injured finger that has prevented quarterbacks from throwing to him in practice (he's still running routes, however). And Ricardo Lockette – quarterback Colin Kaepernick's offseason practice partner – has been slowed by a hip problem.Even before Jenkins was hurt, he hadn't distinguished himself in practices, according to observers.So what does it mean?First of all, the 49ers hope that some of these minor injuries are just that, and players such as Jenkins, Williams, Patton and Lockette will be back at full speed soon and able to make a case for playing time during the...