SBN Houston/Crawfish Boxes' David Coleman has a good piece on Mills and his upcoming tendency to sit Brett Wallace.
We're just seeing a bad side of Brad Mills. Like Jimy Williams, it appears that Mills can't or won't develop young players. That's the only real explanation for why Wallace would lose playing time at this point.
The more I think about this, the more livid I get. The possibility of going from a 110-loss team with Wallace in the lineup to a 100-loss team without him is not enough to justify sitting him. The Astros should be leaving everyone under the age of 26 in the lineup, regardless of matchups/stamina/ability, etc. Have a question about whether or not Chris Johnson can hit? Give him 600 PAs at 3B, and you'll know for 2012. Same thing with Wallace. Take this "opportunity" to see what you have, and use that information going forward.