Houston and Atlanta swapped first rounders, and actually resulted in Houston going down. So they gave up two second rounders... a pretty significant difference.
Cassell has good games against bad defenses. He torched the Jets, who are near the bottom of the league in pass defense, the Cardinals (do you think the Cardinals really wanted anything to do with that game? Had already clinched, it was freezing, had to travel), the Broncos who's defense was among the worst I've ever seen, and he didn't even play that well that game, the Raiders, and... someone else. I understand you can't "take away those games", but outside of those games, he was par for the course, at the very, very best. Lest we forget he was throwing to Wes Welker and Randy Moss.
I very much hope the Chiefs do bring in Cassell, I'd much rather they give up the two first rounders to make an, at best, parallel move from Tyler Thigpen to Matt Cassell. That article is a joke, by the way. Comparing the number of wins between the two? Matt Cassell was QBing a team that went into the season as the Super Bowl favorite... Thigpen was QBing for the team that a lot of people thought had a legitimate shot at going 0-16. Please give up those two first rounders, Pioli! For a team with as many needs as the Chiefs... god I'd love that.