Any success the 49ers have in 2015 will be due in large part to Colin Kaepernick. It's a lot to put on the fifth-year quarterback who has struggled with consistency for much of his career, especially when he'll be without coach Jim Harbaugh, and teammates Frank Gore, Michael Crabtree, Mike Iupati, Patrick Willis, Chris Borland and Justin Smith, who are either playing elsewhere or retired.

A season ago, when the 49ers finished 8-8, Kaepernick had career bests in attempts (478), passing yards (3,369) and rushing yards (639), but he also threw more interceptions, took more sacks and lost more fumbles than at any time during his four years in the league. According to Football Outsiders, Kaepernick ranked 28th in QB efficiency last season, behind Brian Hoyer, Kyle Orton and Mike Glennon.

But according to offensive coordinator Geep Chryst, Kaepernick didn't take a step backwards in 2014.

"And then last year, you're playing with some different sets of challenges," Chryst said, via the MercuryNews.com. There was more change within the offensive line than he had experienced the last couple of years. How does that affect your production as a quarterback? You're behind more often in games. How does that affect your production as a quarterback? I cite the fact that we had six touchdowns nullified by penalty. You plug that back into his formula, he really wasn't ... he didn't regress off his line as much as perceived."

Fair enough, but what does that mean for 2015, when the 49ers will be without much of the talent that helped them get to two NFC Championship games and a Super Bowl?

That's the big question facing Chryst and first-year coach Jim Tomsula, who said in March that Kaepernick not only didn't regress in '14, but he had his best season as a professional.

Can Colin Kaepernick make the 49ers competitive in 2015? (USATSI)
Can Colin Kaepernick make the 49ers competitive in 2015? (USATSI)
"When we go back to the criticisms on Colin -- look we were 8-8 last year. Everyone takes a big bite out of that sandwich," Tomsula said at the time. "Colin touches the ball every play. He's the guy when we win, he gets a little bit more than he probably should, and when we don't win, he gets more than he should. ... Statistically and all that kind of stuff, people throw those out there -- Colin had his best year, okay?"

That's a hard sell; Kaepernick ranked eighth in QB efficiency in 2013 and 13th the season before that. None of that matters now because this 49ers team barely resembles the ones that had so much success under Harbaugh. But Tomsula doesn't sound concerned, probably because he doesn't have a choice.

"I think you're gonna see us get back to the basics, get back to letting our players go out and make plays," he said this spring…."You look at our offense last year. It wasn't I think where it should have been. I think we have better talent than what our results showed.”