He was 22nd in QBR BEFORE today. He's well into the bottom 1/3 of NFL Qbs.
He's 22nd if you include this week, he was 18th when I checked last week. Also, if you separate the 32 starting QBs into thirds, #22 would be the first on the list of those in the bottom 1/3. Obviously the difference is pretty meaningless, but I point it out to show that your exaggeration is an exaggeration. This is the same guy who was #6 last year and the year before. One bad stretch hardly makes him a bottom-tier QB.
And while he is playing poorly, so is the entire offense.
It is virtually impossible for me to believe that everything could go so horribly wrong so quickly. There have to be things we're not seeing. Has the front line changed to the extent where they can no longer protect Kaep? Are his receivers just not paying attention or running the wrong routes? Has Vernon Davis totally lost it? Is there some kind of feud/power struggle going on between Greg Roman and Jim Harbaugh?
Questions, questions, questions ... and no real answers.
The first section of this article goes over some of the many issues the 49ers have faced:
http://grantland.com/the-triangle/week-14-nfl-49ers-raiders-browns-chiefs-colts-cardinals/
But it doesn't have any real answers either.
Glenn's right, the team has suffered more injuries than it did the previous three years under Harbaugh. This has affected the offensive line quite a bit (they lost their starting center who replaced last year's center, leaving a rookie to start the last few games, and Anthony Davis is simply much better than Jonathan Martin).
The defense has somehow played amazingly well through all the injuries, but yesterday they didn't do so well. They're without Bowman for probably all year, and Willis for over half. They're missing their nose tackle for the rest of the year and his backup for all of it so far. Aldon Smith was out for half of the year, and now Ahmad Brooks is in the doghouse. They played Leon McFadden (who?) as a third cornerback yesterday because Ward and Cook are gone for the season and Brock is still out, plus Culliver went out in the middle of the game. Other teams face lots of injuries, too (see Arizona), but it's clear that this is something the 49ers haven't had to deal with to the same level during their run of success.
I also think special teams is a huge problem. They were 30th in
DVOA before this week. That's really bad and is the opposite of what helped the 49ers do well a couple years ago. The poor special teams means that the offense has to drive a lot further a lot more often to get the same amount of points, and they're just not able to do it.
I don't know what the fix is, but it's clearly not to replace Kaepernick. Finding an above average QB is so hard that it doesn't make sense to drop the one you have when there are so many other areas to look at.