Schaub does need to step up in big games. He isn't blameless in all of this. But he is the best we have for sure and I will stand by that. QBs are not perfect. I remember Brees and Ryan both having a 5 interception 0 TD game last season. I remember Peyton throwing 2 interceptions and failing to beat the Ravens even with 14 points from a Kick Returner we cut (our Special Teams coach sucks BTW). It's pretty cool if his worst games are better than some of the elite QB's worst games.
As for finding a replacement QB... You don't find guys late in the draft and groom them. Just doesn't happen. There's only been 1 Tom Brady. If you trade up to select a QB you don't address key positions like a 2nd WR, or O Line. So your rookie QB would have a worthless #2 and a terrible right side of the line. It then takes him 2 years to contend and in that time you lost Andre to father time, now you need another #1 WR. Perpetual rebuilding...
If you let Schaub walk to go after Peyton you likely wouldn't have got Peyton anyway and would have been stuck w/ Yates. People forget we had a top 3 defense in 2011. Look at before and after Schaub, it's pretty noticeable: http://espn.go.com/nfl/team/schedule.../hou/year/2011
Not one single game over 22 point after and only 1 under 22 points before.