Say what you will about budgets and titles, but I doubt heavily that many of the present PS3 owners bought the system for themselves thinking: "Ratchet." Great game though it is. You view Ratchet's bombing in absolute terms; I view in relative terms. It met my sales expectations, for better or worse. Though I'll add I think it'll have decent residuals through year-end...
With the initial reports from Japan and the US it would seem to be in danger of being a money loser despite being critically received by the press. While I admit R&C is has not been mario or halo in the past it has been a solid franchise and I don't think anyone was expecting it to debut at #1 on the chart, but I think even those with subdued expectations were thinking it would crack 100k in the US for its debut. 74,474 is significantly shy of that.