Just a couple of quibbles on this. Even if Pedroia does only hit .250 next year it doesn't necessarily mean they missed an opportunity to move him while he was declining. For one thing, he would still be a well-above-average second baseman, when you factor in his defence.
Also one .250 season wouldn't necessarily mean he was cooked. It could just be an off-season. Ortiz looked to have bottomed out in 2009 hitting .238. This year he's hitting .316.