The Eagles got Washington's 2nd rounder and a 3rd or 4th next year.
Matt Schaub wasn't a 33 going on 34 year-old QB, who has a long list of past injuries, and is in a contract year. Matt Schaub was a 26-year old QB who was being paid a fraction of what McNabb is being paid, and will command this off-season. Peyton Manning and Tom Brady are also in the last year of their deals and (illogically or not) McNabb will want a similar contract money-wise.
The Eagles probably got the most they possibly could have gotten with just the #37 pick, let alone an extra mid-rounder.
The Eagles are in full rebuild mode, trying to rebuild with McNabb as the QB would be dumb for them to do. Trading McNabb is the Eagles finally admitting that they should take a step back before taking a step forward. Hell, the fans agree with that assessment. From all I've gathered, the Eagles fanbase would be totally fine with a 6-10 Kolb season. It may sound silly, but we're pretty tired of the 10-6/11-5 seasons where we're good, but not great, and find a way to lose in heartbreaking fashion in the NFC Playoffs. It's clear this team wasn't going to win a championship in the forseeable future, McNabb isn't getting any younger, and will be looking to get p-a-i-d after this year.
Just made sense to deal him.