The real reason? To throw Alex Smith into the fire as a rookie. Nobody anticipated Alex getting hurt the game after we trade Rattay--obviously we don't trade him. I think coach (and GM) Mike Nolan realized that Rattay probably wouldn't take too well to Alex going above him on the depth chart. That, combined with the fact that the Niners had 4 QBs on their roster allowed Nolan to make the decision to send Rattay on his way.
Barlow has sucked since Garrison Hearst left the Niners, Gore is a rookie (but has shown flashes of being a good RB), Battle has struggled to learn the WR position in the pros (I say Brandon Lloyd is our #1 WR). Our O-Line leaves a lot to be desired, which is not helping our offense, but we could also use a little more talent at the skill positions (in particular wide receiver). We're also missing Eric Johnson like nobody's business.