SANTA CLARA – Greg Roman was discussing Colin Kaepernick and the young quarterback's growing comfort in the 49ers' offense two weeks ago when he broke off in mid-sentence.

"I hate to use that word, 'comfort,' " the 49ers' offensive coordinator said. "It's more of a familiarity. Can we strike that word from the record? 'Comfort'?"

It was as if Roman wanted to wash his own mouth out with soap. Why does he loathe the word?

Said Roman: "Because comfort precedes the fall."

Pregnant pause. Now cue the dramatic music.

Neither Roman nor coach Jim Harbaugh nor anyone on the 49ers has explained why the team decided to move ahead with Kaepernick instead of reliable and battle-tested Alex Smith, but their discomfort with the notion of comfort goes a long way.

The 49ers probably would have been fine with Smith running the offense. They probably would have won the division and made the playoffs. But the 49ers believe they always should be tinkering, always pushing, always trying to move forward. And they suspected they could go deeper into the playoffs with Kaepernick.

Never be satisfied. Never be content. Never leave well enough alone.

That theory will be tested over the next two weeks.

The stakes aren't quite as high as the playoffs, but games at New England and at Seattle are as close as you can get to postseason conditions. Both will serve as litmus tests for Kaepernick and provide a sense of whether Harbaugh and Roman made the correct move.

Pressure? The 49ers will play two straight prime-time games, both are against playoff-caliber opponents in their stadiums. The Patriots have won their past 20 home games in the month of December; the Seahawks play in, by far, the loudest open-air stadium and are undefeated at home this season.

Both games also are rife with postseason implications.

Win Sunday against the Patriots and the 49ers guarantee themselves at least a wild-card spot. Win the next two games and they take the division.

Lose the next two? It raises the possibility of a long and lonely January.

All of that has been heaped on the shoulders of a guy making the fifth start of his career. How green is Kaepernick? His 134 career pass attempts are the fewest of any quarterback starting in Week 15. By contrast, Tom Brady, his opponent Sunday, has attempted 5,816 passes.

The 49ers coaches, however, have faith in Kaepernick. And it's clear key players do, too.

Harbaugh has said he took the pulse of his team before choosing Kaepernick over Smith. You have to assume one of the players he spoke to was Randy Moss, who along with Frank Gore, Justin Smith and Patrick Willis has the most sway inside the 49ers' locker room.

Moss on Wednesday said he was most impressed by the way Kaepernick came off the sideline and led the offense when Smith was knocked out of the Nov. 11 game against St. Louis.

"Anytime a guy can come in and lead like that – and I don't mean verbally but leading by example – is what we as football players look for in a player," Moss said. "Especially in a quarterback. So I really just compliment his leadership and going out there and leading our offense up and down the field."

After his brief media session – Moss grants interviews about as often as North Korean leader Kim Jong Un – the veteran wide receiver walked past a wall and into the 49ers' locker room.

On the inside of that wall is a 6-foot-by-6-foot sign that Harbaugh installed last year. Players see it every time they step out of the locker room and onto the practice field. It reads: "You are getting better or you are getting worse. You never stay the same."

That is: Don't get comfortable.

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