The San Francisco 49ers, though unusually healthy in recent seasons, had a hard time recovering from injuries to return specialist Ted Ginn Jr. and top defensive lineman Justin Smith over the past two seasons.Bill Barnwell drives home that point in his latest piece for Grantland, one calling into question how the 49ers will recover from Michael Crabtree's injury.2012 Michael Crabtree ReceivingThe piece also touched upon a subject we've discussed in some detail around here: Crabtree's improved production with Colin Kaepernick at quarterback.