At this point, I think we can safely rule out Brooks Bollinger as having figured in the Vikings' starting QB discussion. Most likely, Bollinger would not have been able to play due to injury, but even if he was physically able to play, his inability to practice this week means that he shouldn't have been considered. Honestly, he's just not good enough to play at anything less than 100%.
So that leaves Brad Childress with the choice between Tarvaris Jackson and Brad Johnson. And it's looking more and more like he's made the wrong choice. I just don't understand it. Brad Johnson's 71.2 QB rating so far this year is the third worst by a Vikings' QB with more than one start in the last 15 years. Spurgeon Wynn had the worst, posting a 38.6 rating in his three starts. Of actual quarterbacks, only Warren Moon in 1996 (68.7 QB rating in seven games) had a worse rating. That year, Moon suffered a broken collarbone early on, and was never the same, eventually losing his job to Brad Johnson after his return from injury.
Basically, no Vikings' quarterback has been allowed to play this much while playing this poorly in the last 15 years. There's a reason for that: when a quarterback strings together awful performance after awful performance, his backup simply cannot do any worse, especially when the backup is a talented rookie that has looked good in limited playing time. Bill Parcells and Mike Shanahan, two Hall of Fame coaches, faced similar quarterback issues, and both made the same decision--they benched their veteran in favor of their young, talented back up. If onlyBrad Childress would follow their lead, end the Brad Johnson era and kick off the Tarvaris Revolution, the Vikings might actually be able to seize the opportunity that their NFC rivals are providing for them.
[Edit: Mark Craig tried to explain the logic. I'm not sure if I want to agree with him, ignore him or just give up on the season. I hate the Vikings sometimes.]