Grant Cohn: 49ers know questions, but can they find answers?

Remember dead week in college before finals?

This is dead six weeks for the San Francisco 49ers. They have the next month and a half off to prepare for the exam that will make or break their 2015 season.

What questions will be on that test when the Niners arrive for training camp?

In ascending order of importance, here are the top five questions the Niners must answer before the season begins.

5. Who will be the No. 3 receiver?

Anquan Boldin and Torrey Smith are the starters — no question about that. And there's no question how good they'll be, either. They're a winning combination, the starters for the 2012 Baltimore Ravens, the team that beat the 49ers in the Super Bowl.

No wonder the Niners wanted Boldin and Smith. They are the best tandem of starting receivers the 49ers have had since Terrell Owens and Jerry Rice in 2000.

But who will be the Niners No. 3 receiver? That job is up for grabs. The top candidates seem to be veteran Jerome Simpson and undrafted rookie DeAndrew White.

White might have been the 49ers' best receiver during the six practices open to the media this offseason — even better than Boldin and Smith. White never dropped a pass during team drills and quickly became a favorite target of every Niners quarterback. On the final day of minicamp, White was playing with the first-team offense.

White's issue is durability — he suffered injury after injury during college at University of Alabama, meaning he may be injury prone. Will he play well when the hitting starts, or is he a flag-football superstar?

Simpson is a proven NFL receiver, starting 32 games since 2011. He didn't play last season — the Minnesota Vikings cut him before he finished serving a three-game suspension at the beginning of the season for violating the NFL's substance abuse policy.

But Simpson is only 29. His most recent season in the NFL (2013) he was an elite deep threat, making 10 catches of 20 or more yards — the same number of deep catches Torrey Smith made that season.

Simpson never has played with a quarterback as good as Colin Kaepernick. Will 2015 be Simpson's best season yet?

4. How good are the linebackers?

The 49ers have a linebacker-oriented defense. When the defense was at its best a few seasons ago, they had four All-Pro caliber linebackers — Ahmad Brooks, Patrick Willis, NaVorro Bowman and Aldon Smith.

Willis retired this offseason, but the other three are still here. How good will they be in 2015?

Brooks was out of shape last season and lost his starting job to rookie fifth-round pick Aaron Lynch. If Brooks can get himself in shape, he may retake his starting job. He's only 31.

Bowman tore his ACL and MCL in the 2014 NFC championship game, and he's still recovering. He wears a knee brace during team drills which inhibits his ability to cut and change directions. He's a liability in coverage with that brace. When will he be able to play without it?

And when will the real Aldon Smith show his face? The NFL suspended him for the first nine games last season. When he returned to the team, he seemed like just another guy. He recorded only two sacks. Teams shut him down easily.

Can he be the All-Pro player he used to be? If so, the Niners will be dangerous next season.

3. Which blocking scheme can the 49ers master?

Gap blocking and zone blocking — those are the only two blocking schemes.

Under Jim Harbaugh, the 49ers primarily were a gap-blocking offense. This offseason, the Niners mostly practiced zone-blocking — the scheme Mike Shanahan and Gary Kubiak made famous.

According to 49ers quarterback coach Steve Logan, the new coaching staff wants to use both blocking schemes. 'The ability to blend those, that's where you're going to find out how good you are,' he said.

Blending the schemes can be extremely difficult. Kubiak coaches only zone blocking because he wants to make sure his team masters it. When a team tries to use both schemes, they risk mastering neither.

The Niners don't yet know which scheme will be more successful for them. They have to play full-speed tackle football during preseason and they need to experiment.

2. Can the offensive line protect Colin Kaepernick?

It certainly couldn't last season, which is the main reason Kaepernick had his worst season as a starter. Defenses sacked him 52 times — more than three times per game.

The Niners had one of the poorest pass-blocking offensive lines in 2014. Will it improve next season? They lost Pro-Bowl guard Mike Iupati, who signed with the Arizona Cardinals, and premier right tackle Anthony Davis, who retired at the age of 25.

The Niners don't seem to have upgrades for those two, who will be tough to replace. Both were former top-20 draft picks in 2010.

And both were great run blockers, but both struggled in pass protection. Iupati gave up seven sacks in 15 games last season, and Davis gave up three sacks in seven games — he missed the other nine due to injuries.

Is it possible the losses of Iupati and Davis have improved the Niners' ability to protect the quarterback?

1. Will Colin Kaepernick benefit from the new offensive system?

The 49ers are building their new offense around Kaepernick's strengths, meaning his legs. We should see more rollout passes and read-option runs from him than we saw the past two seasons.

Which is all well and good, but the Niners also will expose him to more hits. That's the tradeoff. The previous coaching staff protected Kaepernick during the regular season by rarely calling read options and mostly keeping him in the pocket. Kaepernick struggled with this style of offense, but at least he never got hurt.

Right now, opposing linebackers and safeties must be licking their chops. They know Kaepernick will run more next season, and they know they'll get their shot to knock him out.

Can Kaepernick avoid the knockout blow? Can the coaching staff keep him alive?

Grant Cohn writes sports columns and the 'Inside the 49ers' blog for The Press Democrat's website. You can reach him at grantcohn@gmail.com.