Not only that all those developers that went to Sony were now going to MS, remember the 50 million dollars exclusive GTA DLC for 360, remember how new finaly Fantasy is not a complete Sony exclusive anymore??? Or how about the huge marketing plans and guaranteed success of Gears of War. Not really the signs of an underdog.
What does this have to do with the 360 being an underdog coming into this generation? They made strategic investments to push their product forward, but none of your points were even known before/at the 360's beginning. They are more recent developments. Nintendo was the true underdog of this generation though; remember the rumours that Nintendo wasn't even going to make hardware anymore during the gloomy Gamecube days??
Anyways, to go back on-topic.... It's good to see a lot of software being moved. I think the Orange Box could break-through because I believe it's only $20 most places (got mine for $10 on boxing day, talk about a deal).