If the metric is out of 100 then I think all of these are pretty disappointing. But at the same time they don't mean shit really.
Killzone is a launch FPS so it will sell. Look at how much Resistance sold compared to Resistance 2 and 3.
Forza is a sim racer, not as big a genre as FPS but Forza games sell 4-5 million a pop it seems.
Who knows with Ryse.
Knack and DriveClub doing so poorly is not a surprise to me. Knack looks boring as hell and DriveClub looks downright terrible imho.







