I consider it a bomb because a franchaise that seemed to be Xbox's second most important should be able to sell more than that, even in March. If Splinter Cell 3 launches this fall and sells a million all at once, I guess they just launched PT at the wrong time. But if it sells similarly, it might be possible that a lot of people that bought the first one weren't that crazy about it and aren't going to continue with the franchaise. Hell, I wouldn't have bought Pandora Tomorrow without the xbox live multiplayer.
And as a side note, the PS2 version of SC1 launched at the same time of the year as the PS2 PT did, and the PS2 PT is selling worse than the first one at the exact same time of the year.