Staff writer Matthew Barrows analyzes the 49ers as training camp opens:

1. Who's No. 2?

Alex Smith is the clear No. 1 quarterback. The battle to be his backup, however, promises to be one of the more intriguing training camp competitions. Colin Kaepernick, the 49ers' second-round pick in 2011, heads into camp in that position, but he has pressure from head coach Jim Harbaugh's former protégé Josh Johnson and from dark-horse candidate Scott Tolzien. Exhibition game performances will go a long way in determining the final order. Kaepernick's physical gifts – arm strength and running ability – are impressive, but he must show he can harness that power. Tolzien is eligible for the practice squad.

2. Can Moss recapture his past?

The 49ers want to boost a passing attack that was only ho-hum last season. Their potential savior? A man who spent the 2011 season at home in West Virginia. Randy Moss looked like the Randy Moss of old during spring practices in making circus catches that made his quarterbacks look good. But those sessions were all done without pads. The next test for the 35-year-old wideout is full-contact drills in which defensive teammates will be sure to challenge the lanky Moss at the line of scrimmage. The 49ers are betting that Moss will be motivated to put an exclamation point on what has been a Hall of Fame career.

3. How will carries be divided?

The days when running back Frank Gore handled the lion's share of the 49ers' rushes appear to be over. Gore still will be the starting running back, and the 49ers still will run the ball more than most teams. But the 49ers also will have more talent in the backfield than they've had in recent memory. Second-year player Kendall Hunter's workload promises to increase after an impressive rookie season. And the team will carve out carries for second-round draft pick LaMichael James and free-agent addition Brandon Jacobs. Exactly how those players will be used remains to be seen.

4. Can the defense get better?

The sole change to the 49ers' ferocious 2011 defense is that Aldon Smith will start at outside linebacker after playing less than half of the team's defensive snaps last year. That Smith managed a franchise-record 14 sacks for a rookie despite his limited playing time bodes well. So does the fact that he'll be lining up next to Justin Smith, who is a legitimate contender to win the league's Defensive Player of the Year award.

5. Will the secondary hold up?

Last year, the team's defense was nearly invincible against the run. Against the pass, however, the 49ers were mere mortals, finishing 16th in the league in yards allowed through the air. Six interceptions apiece by safety Dashon Goldson and cornerback Carlos Rogers helped mitigate those yards, but the 49ers' secondary will be under more pressure this year. The team will face all of the NFL's most prolific passing attacks this season, beginning in Week 1 against Aaron Rodgers and the Green Bay Packers.

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