That is the key question facing the 49ers as they prepare for the Packers. If Smith is healthy, the 49ers will have a formidable pass rush and can harass Aaron Rodgers and degrade his passing game. A healthy Justin Smith makes Aldon Smith a better sacker of quarterbacks. If Smith is healthy, the Niners can almost certainly negate the Packers’ run game.

But if Smith is not healthy — if he is not Justin Smith — the 49ers’ defense is no big deal. Think back to the second half of the Patriots game on Dec. 16 and the Seahawks game on Dec. 23 when Smith could not play because he injured his left triceps.

The 49ers really need Justin Smith to be Justin Smith.

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