Most teams facing a quarterback controversy are, in reality, resigned to this fate: they actually have zero starting-caliber QBs instead of two (see: New York Jets). Vikings fans have lived through their share of these dilemmas; lest we forget, the back-and-forth duo of Tarvaris Jackson and Gus Frerotte in 2008, when the Vikings somehow won 10 games.
We also are accustomed to hearing this wisdom from virtually every coach in the land: a starting player should not lose his or her job because of an injury. When healthy, the spot is theirs to reclaim.
The combination of Points A and B make the San Francisco 49ers' sudden situation so odd -- and interesting.
When starter Alex Smith was knocked out last week because of a concussion, second-year QB Colin Kaepernick took over. He made his first start Monday Night Football against the Bears and looked fantastic. Still, coaches tend to temper enthusiasm for a backup QB who shines because the sample size is small and consequences of rocking the boat are potentially large.
Noted: Jim Harbaugh does not play by conventional rules.
"I usually tend to go with the guy that has the hot hand, and we have two quarterbacks that have a hot hand," Harbaugh said about the team's starting QB situation going forward, adding later that "there's no rule" about a QB losing his spot to injury.
If Smith doesn't heal, it's a moot point. If he is cleared, however, it becomes the rarest of QB controversies. Smith, labeled a "game manager" last year as the 49ers came within a whisper of the Super Bowl, is third in the NFL in passer rating this season. If you prefer Total QBR -- an ESPN stat intended to measure a QB's true impact on a game, Smith is ninth in the NFL, up from 22nd a year ago. He is not an elite quarterback, but he was certainly above average this season in leading San Francisco to a 6-2 record before the game in which he was injured.
Kaepernick is younger and more dynamic -- able to make plays with his arms and feet. The 49ers clearly coveted him in 2011, when they traded up to take him with the 36th overall pick. But he's still unproven long-term and San Francisco doesn't know how he will respond to adversity. Unlike Smith, he has yet to go through the wringer.
So even if the contending 49ers have two good choices (when both are healthy), Harbaugh still can make the wrong one -- and open himself up to plenty of criticism in the process.