SANTA CLARA – The biggest and most momentous play from last weekend's divisional playoff game in San Francisco saw Colin Kaepernick break to his right and then burst downfield on a 56-yard touchdown run.

Too bad most of the players on the field missed it.

Half of the Packers' defense, including – critically for them – linebackers Brad Jones and Erik Walden and strong safety Morgan Burnett, thought Kaepernick had handed the ball to LaMichael James on an inside run. They all converged on the diminutive running back, who was hunched over a football that wasn't there. Jones actually crouched down to tackle James before he discovered the ruse.

The Packers defenders shouldn't feel too bad. The 49ers' offensive linemen didn't know exactly what was going on, either on that particular read-option play or others throughout the night.

"About when he was on the 10-yard line," guard Alex Boone said when asked when he realized Kaepernick had kept the ball.

It's a magic trick Kaepernick has been perfecting for the past six years dating back to his college days at Nevada.

The root of it is a simple dilemma – either the quarterback gives the ball to the tailback or he keeps it. But it's enough to at least make defensive players freeze while they determine which transaction has indeed occurred.

At best, outside defenders like Walden will crack down to stop the inside run, giving the quarterback a wide-open running lane to the outside.

"It took awhile for Kap to get used to it, but once he did, he was great," said former Nevada coach Chris Ault, who began teaching Kaepernick the trick in 2006. "There's a feel to it – when to fake, when to keep. He's the right guy to run it. He has a sense of the total concept."

Kaepernick said he grew up watching quarterbacks like Randall Cunningham and Donovan McNabb. He liked them, he said, because they were complete quarterbacks who could beat opponents with their arms and legs.

Those quarterbacks also were adept at play-action passing, at disguising plays and at hiding the ball from defenders. Usually, those skills come with veteran experience. Kaepernick entered the league with them.

Offensive coordinator Greg Roman noted that being quick and decisive is just as important as sleight-of-hand.

"It's not something that you can easily write on paper to describe," he said. "But it's a matter of pressure. The quarterback has the ball, controls the ball, and when he pulls it, he's yanking that thing out. There is no indecision. He is ripping that thing out with conviction, or he lays it in there gently. So, there's definitely a stark contrast between the two."

Is there ever a tug-of-war over the ball with running back Frank Gore?

"There's times where he's trying to take it and I'm trying to take it," Kaepernick said. "But at that point, he sees something, so you're going to give him the ball. He's going to be a Hall of Fame running back. He knows what he's doing."

The offensive linemen, meanwhile, have their backs to the play and usually don't know who has the ball. Boone said their assignment is simply to stay on their blocks and let the runners figure out where the running lanes are developing.

"Sometimes I think that Frank does have the ball because everyone's chasing Frank," Boone said. "So I'm chasing Frank. … And then I see Kap's got the ball on the other side and I'm like, 'Oh, he has it.' "

Center Jonathan Goodwin said the defenders often show who has the ball.

"There were a couple of times in that game where La-Michael would run by and the guy didn't try to tackle him," he said. "I figured Kap had the ball. I think on Kap's long touchdown run, LaMichael ran by, and I saw him and I could tell he didn't have the ball."

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