Apparently a tough loss isn't it - yet.
Kaepernick's crucial turnover on a botched pitch attempt led to a touchdown and ensuing two-point conversion to tie the game with three minutes remaining as the 49ers (8-3-1) eventually fell 16-13 in overtime at St. Louis last week.
That error put a damper on an otherwise solid performance for Kaepernick, who finished 21 of 32 for 208 yards while running for 84 more.
"Can't make mistakes. That's the biggest thing," Kaepernick said. "For the most part I felt my reads were good, got through progressions well. That's something I want to continue to do going forward."
He'll get a chance to do just that Sunday as Harbaugh decided to stick with Kaepernick, who took the reigns after Smith suffered a concussion during a 24-all tie with the Rams on Nov. 11.
Kaepernick has thrown three TD passes and ran for two more scores with a 97.4 passer rating since entering that contest, keeping Smith on the bench for at least the start of another week.
"Just a winning quarterback performance in tough circumstances," Harbaugh said. "In the evaluation, I thought Colin played well, did a lot of really good things, made some good decisions. I thought some real positives to take away from his performance.
"We've got faith and trust in Colin in the way he's played. Therefore, (he'll get) another start this week."
The 49ers' loss ended a five-game unbeaten streak and tightened the NFC West race after Seattle (7-5) beat Chicago last week. Frank Gore averaged a season-worst 2.5 yards per carry and finished with 58 yards and a touchdown, though Harbaugh took much of the blame for the defeat.
"It's accountability, taking responsibility," said Harbaugh, whose team committed a season-worst 11 penalties. "We all looked at the fact that we didn't win the game, we didn't finish like we were supposed to."
Wide receiver Mario Manningham did not practice Wednesday due to a shoulder injury and is questionable for Sunday, though Miami's latest injury might be more difficult to overcome.
Left tackle Jake Long was placed on injured reserve Tuesday after suffering a torn triceps in last week's 23-16 loss to New England. Rookie Jonathan Martin will shift from the right side to replace Long.
It's tough news for the Dolphins (5-7), who already face an uphill climb to reach the postseason while preparing for a tough matchup against San Francisco, which possesses the league's second-best defense allowing 279.6 yards per game.
Reggie Bush knows he's in for a battle as the 49ers are allowing an average of only 90.6 yards on the ground.
"This is going to be a tough game, a grind-it-out football game," Bush said. "It's going to come down to our ability to execute and how bad we want to win this football game."
The Dolphins' offense as a whole hasn't been fantastic, ranking 28th averaging 317.6 yards.
"We haven't really hit a consistent stride at any point in the season," Bush said. "We've just kind of got to find a happy medium. We've just kind of got to find a consistency about our team that we can feel good."
"Whatever way it is we have to find a way to put more points on the board," Tannehill said. "Our run game has picked up the past two weeks, and I have to get the passing game going consistently throughout games."
Coach Joe Philbin said miscues like last week, which included a botched punt and a Tannehill fumble, can't happen against San Francisco.
"Too many mistakes," Philbin said. "To beat a good opponent in December, you have to play better."
Sunday marks the first meeting between the teams since the Dolphins beat the visiting 49ers 14-9 on Dec. 14, 2008.