OK, let's reassess.
A team with an 18-16 record and who had to win the play-in game. The worst of all #16 seeds.
A team that a lot of people thought might not even make the tournament after losing the Pac-10 tournament final. The worst #8 seed.
Purdue was maybe a #2 with Hummel. Without him, let's be honest--they were probably a #7 seed or so. Go back and watch the Minnesota game in the BTT. So I think by far Purdue was the worst #4 seed. And, by the way, Kramer was starting all year, so I'm not sure what you mean by "Kramer filling in for Hummel."
Why did they impress you most? They were about the only team in the tournament with an easier path than Duke. They beat Sam Houston State, Old Dominion, and St. Marys. Those three wins are not impressive. Oh yeah, they also fell apart like a cheap suit the first time they were in a tight situation in the tournament. Maybe they weren't the worst #3 seed (NM was pretty weak, IMO), but this wasn't a traditional tough team that you see as a #3 seed--and Duke was lucky not to face a better team to go to the Final Four.
Yeah, a team that most thought was deserving of a #1...back when they, you know, actually had their starting point guard. Are you really trying to say that doesn't change anything? I don't remember Nolan Smith going down due to injury for Duke.
Butler played with a ton of heart, and played a really tough game. However, they were pretty overmatched size-wise in that game. Certainly, as far as national championship games go, I think Duke got pretty lucky having to face Butler in the NC game.